Gentoo Linux amd64 Handbook: Installing Gentoo

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Introduction

Welcome

Welcome to Gentoo! Gentoo is a free operating system based on Linux that can be automatically optimized and customized for just about any application or need. It is built on an ecosystem of free software and does not hide what is running beneath the hood from its users.

Openness

Gentoo's premier tools are built from simple programming languages. Portage, Gentoo's package maintenance system, is written in Python. Ebuilds, which provide package definitions for Portage are written in bash. Our users are encouraged to review, modify, and enhance the source code for all parts of Gentoo.

By default, packages are only patched when necessary to fix bugs or provide interoperability within Gentoo. They are installed to the system by compiling source code provided by upstream projects into binary format (although support for precompiled binary packages is included too). Configuring Gentoo happens through text files.

For the above reasons and others: openness is built-in as a design principle.

Choice

Choice is another Gentoo design principle.

When installing Gentoo, choice is made clear throughout the Handbook. System administrators can choose two fully supported init systems (Gentoo's own OpenRC and Freedesktop.org's systemd), partition structure for storage disk(s), what file systems to use on the disk(s), a target system profile, remove or add features on a global (system-wide) or package specific level via USE flags, bootloader, network management utility, and much, much more.

As a development philosophy, Gentoo's authors try to avoid forcing users onto a specific system profile or desktop environment. If something is offered in the GNU/Linux ecosystem, it's likely available in Gentoo. If not, then we'd love to see it so. For new package requests please file a bug report or create your own ebuild repository.

Power

Being a source-based operating system allows Gentoo to be ported onto new computer instruction set architectures and also allows all installed packages to be tuned. This strength surfaces another Gentoo design principle: power.

A system administrator who has successfully installed and customized Gentoo has compiled a tailored operating system from source code. The entire operating system can be tuned at a binary level via the mechanisms included in Portage's make.conf file. If so desired, adjustments can be made on a per-package basis, or a package group basis. In fact, entire sets of functionality can be added or removed using USE flags.

It is very important that the Handbook reader understands that these design principles are what makes Gentoo unique. With the principles of great power, many choices, and extreme openness highlighted, diligence, thought, and intentionality should be employed while using Gentoo.

How the installation is structured

The Gentoo Installation can be seen as a 10-step procedure, corresponding to the next set of chapters. Each step results in a certain state:

Step Result
1 The user is in a working environment ready to install Gentoo.
2 The Internet connection is ready to install Gentoo.
3 The hard disks are initialized to host the Gentoo installation.
4 The installation environment is prepared and the user is ready to chroot into the new environment.
5 Core packages, which are the same on all Gentoo installations, are installed.
6 The Linux kernel is installed.
7 Most of the Gentoo system configuration files are created.
8 The necessary system tools are installed.
9 The proper boot loader has been installed and configured.
10 The freshly installed Gentoo Linux environment is ready to be explored.

Whenever a certain choice is presented the handbook will try to explain the pros and cons of each choice. Although the text then continues with a default choice (identified by "Default: " in the title), the other possibilities will be documented as well (marked by "Alternative: " in the title). Do not think that the default is what Gentoo recommends. It is, however, the choice that Gentoo believes most users will make.

Sometimes an optional step can be followed. Such steps are marked as "Optional: " and are therefore not needed to install Gentoo. However, some optional steps are dependent on a previously made decision. The instructions will inform the reader when this happens, both when the decision is made, and right before the optional step is described.

Installation options for Gentoo

Gentoo can be installed in many different ways. It can be downloaded and installed from official Gentoo installation media such as our bootable ISO images. The installation media can be installed on a USB stick or accessed via a netbooted environment. Alternatively, Gentoo can be installed from non-official media such as an already installed distribution or a non-Gentoo bootable disk (such as Knoppix).

This document covers the installation using official Gentoo Installation media or, in certain cases, netbooting.

Note
For help on the other installation approaches, including using non-Gentoo bootable media, please read our Alternative installation guide.

We also provide a Gentoo installation tips and tricks document that might be useful.

Troubles

If a problem is found in the installation (or in the installation documentation), please visit our bug tracking system and check if the bug is known. If not, please create a bug report for it so we can take care of it. Do not be afraid of the developers who are assigned to the bugs - they (generally) don't eat people.

Although this document is architecture-specific, it may contain references to other architectures as well, because large parts of the Gentoo Handbook use text that is identical for all architectures (to avoid duplication of effort). Such references have been kept to a minimum, to avoid confusion.

If there is some uncertainty about whether or not the problem is a user-problem (some error made despite having read the documentation carefully) or a software-problem (some error we made despite having tested the installation/documentation carefully) everybody is welcome to join the #gentoo (webchat) channel on irc.libera.chat. Of course, everyone is welcome otherwise too as our chat channel covers the broad Gentoo spectrum.

Speaking of which, if there are any additional questions regarding Gentoo, check out the Frequently Asked Questions article. There are also FAQs on the Gentoo Forums.





Hardware requirements

Before proceeding with the installation process, minimum hardware requirements should be met in order to successfully install Gentoo for the amd64 system architecture.


AMD64 livedisk hardware requirements
Minimal CD LiveDVD
CPU Any x86-64 CPU, both AMD64 and Intel 64
Memory 2 GB
Disk space 8 GB (excluding swap space)
Swap space At least 2 GB

The AMD64 project is a good place to be for more information about Gentoo's amd64 support.


Gentoo Linux installation media

Tip
While it's recommended to use the official Gentoo boot media when installing, it's possible to use other installation environments. However, there is no guarantee they will contain required components. If an alternate install environment is used, skip to Preparing the disks.

Minimal installation CD

The Gentoo minimal installation CD is a small, bootable image: a self-contained Gentoo environment. This image is maintained by Gentoo developers and designed to allow any user with an Internet connection to install Gentoo. During the boot process, the hardware is detected, and appropriate drivers are automatically loaded.

Minimal Installation CD releases are named using the format: install-<arch>-minimal-<release timestamp>.iso.

The Gentoo LiveGUI

Some users may find it easier to install Gentoo using the LiveGUI, which provides a KDE desktop environment. In addition to providing a useful graphical environment, the LiveGUI has more kernel modules and firmware, which can help with using modern Wi-Fi chipsets.

Note
The Gentoo LiveGUI USB image is built for amd64 and arm64 platforms weekly.

What are stage files?

A stage file is an archive which serves as the seed for a Gentoo environment.

Stage 3 files can be downloaded from releases/amd64/autobuilds/ on any of the official Gentoo mirrors. Stages are updated frequently and are therefore not included within official live images.

Tip
For now, stage files can be ignored. They will be described in greater detail later when they are needed
Note
Historically, the handbook described installation steps for stage files with versions lower than 3. These stages contained environments unsuitable for typical installations, and are no longer covered in the handbook.

Downloading

Obtain the media

The default installation media used by Gentoo Linux are the minimal installation CDs, which provide a very small, bootable, Gentoo Linux environment. This environment contains the necessary tools to install Gentoo. The images themselves can be downloaded from the downloads page (recommended) or by manually browsing to the ISO location on one of the many available mirrors.

Navigating Gentoo mirrors

If downloading from a mirror, the minimal installation CDs can be found by:

  1. Connect to the mirror, typically using a local one found at Gentoo source mirrors.
  2. Navigate to the releases/ directory.
  3. Select the directory for the relevant target architecture (such as amd64/).
  4. Select the autobuilds/ directory.
  5. For amd64 and x86 architectures select either the current-install-amd64-minimal/ or current-install-x86-minimal/ directory (respectively). For all other architectures navigate to the current-iso/ directory.
Note
Some target architectures such as arm, mips, and s390 will not have minimal install CDs. At this time the Gentoo Release Engineering project does not support building .iso files for these targets.

Inside this location, the installation media file is the file with the .iso suffix. For instance, take a look at the following listing:

CODE Example list of downloadable files at releases/amd64/autobuilds/current-install-amd64-minimal/
[TXT]	install-amd64-minimal-20231112T170154Z.iso.asc	        2023-11-12 20:41        488
[TXT]	install-amd64-minimal-20231119T164701Z.iso.asc	        2023-11-19 18:41        488
[TXT]	install-amd64-minimal-20231126T163200Z.iso.asc	        2023-11-26 18:41        488
[TXT]	install-amd64-minimal-20231203T170204Z.iso.asc	        2023-12-03 18:41        488
[TXT]	install-amd64-minimal-20231210T170356Z.iso.asc	        2023-12-10 19:01        488
[TXT]	install-amd64-minimal-20231217T170203Z.iso.asc	        2023-12-17 20:01        488
[TXT]	install-amd64-minimal-20231224T164659Z.iso.asc	        2023-12-24 20:41        488
[TXT]	install-amd64-minimal-20231231T163203Z.iso.asc	        2023-12-31 19:01        488
[ ]     install-amd64-minimal-20240107T170309Z.iso              2024-01-07 20:42        466M
[ ]     install-amd64-minimal-20240107T170309Z.iso.CONTENTS.gz	2024-01-07 20:42        9.8K
[ ]     install-amd64-minimal-20240107T170309Z.iso.DIGESTS      2024-01-07 21:01        1.3K
[TXT]   install-amd64-minimal-20240107T170309Z.iso.asc	        2024-01-07 21:01        488
[ ]     install-amd64-minimal-20240107T170309Z.iso.sha256       2024-01-07 21:01        660
[TXT]	latest-install-amd64-minimal.txt                        2024-01-08 02:01        653

In the above example, the install-amd64-minimal-20240107T170309Z.iso file is the minimal installation CD itself. But as can be seen, other related files exist as well:

  • A .CONTENTS.gz file which is a gz-compressed text file listing all files available on the installation media. This file can be useful to verify if particular firmware or drivers are available on the installation media before downloading it.
  • A .DIGESTS file which contains the hash of the ISO file itself, in various hashing formats/algorithms. This file can be used to verify ISO file integrity.
  • A .asc file which is a cryptographic signature of the ISO file. This can be used to verify image integrity and authenticity - that the download is indeed provided by the Gentoo Release Engineering team, free from tampering.

Ignore the other files available at this location for now - those will come back when the installation has proceeded further. Download the .iso file and, if verification of the download is wanted, download the .iso.asc file for the .iso file as well.

Tip
The .DIGESTS file is only needed if the signature in the .iso.asc file is not verified.

Verifying the downloaded files

Note
This is an optional step and not necessary to install Gentoo Linux. However, it is recommended as it ensures that the downloaded file is not corrupt and has indeed been provided by the Gentoo Infrastructure team.

The .asc file provides a cryptographic signature of the ISO. By validating it, one can make sure that the installation file is provided by the Gentoo Release Engineering team and is intact and unmodified.

Microsoft Windows-based verification

To first verify the cryptographic signature, tools such as GPG4Win can be used. After installation, the public keys of the Gentoo Release Engineering team need to be imported. The list of keys is available on the signatures page. Once imported, the user can then verify the signature in the .asc file.

Linux based verification

On a Linux system, the most common method for verifying the cryptographic signature is to use the app-crypt/gnupg software. With this package installed, the following command can be used to verify the cryptographic signature in the .asc file.

Tip
When importing Gentoo keys, verify that the fingerprint (BB572E0E2D182910) matches.

Gentoo keys can be downloaded from hkps://keys.gentoo.org using fingerprints available on the signatures page:

user $gpg --keyserver hkps://keys.gentoo.org --recv-keys 13EBBDBEDE7A12775DFDB1BABB572E0E2D182910
gpg: directory '/root/.gnupg' created
gpg: keybox '/root/.gnupg/pubring.kbx' created
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key BB572E0E2D182910: public key "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" imported
gpg: Total number processed: 1
gpg:               imported: 1

Alternatively you can use instead the WKD to download the key:

user $gpg --auto-key-locate=clear,nodefault,wkd --locate-key releng@gentoo.org
gpg: key 9E6438C817072058: public key "Gentoo Linux Release Engineering (Gentoo Linux Release Signing Key) <releng@gentoo.org>" imported
gpg: key BB572E0E2D182910: public key "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" imported
gpg: Total number processed: 2
gpg:               imported: 2
gpg: no ultimately trusted keys found
pub   dsa1024 2004-07-20 [SC] [expires: 2025-07-01]
      D99EAC7379A850BCE47DA5F29E6438C817072058
uid           [ unknown] Gentoo Linux Release Engineering (Gentoo Linux Release Signing Key) <releng@gentoo.org>
sub   elg2048 2004-07-20 [E] [expires: 2025-07-01]

Or if using official Gentoo release media, import the key from /usr/share/openpgp-keys/gentoo-release.asc (provided by sec-keys/openpgp-keys-gentoo-release):

user $gpg --import /usr/share/openpgp-keys/gentoo-release.asc
gpg: directory '/home/larry/.gnupg' created
gpg: keybox '/home/larry/.gnupg/pubring.kbx' created
gpg: key DB6B8C1F96D8BF6D: 2 signatures not checked due to missing keys
gpg: /home/larry/.gnupg/trustdb.gpg: trustdb created
gpg: key DB6B8C1F96D8BF6D: public key "Gentoo ebuild repository signing key (Automated Signing Key) <infrastructure@gentoo.org>" imported
gpg: key 9E6438C817072058: 3 signatures not checked due to missing keys
gpg: key 9E6438C817072058: public key "Gentoo Linux Release Engineering (Gentoo Linux Release Signing Key) <releng@gentoo.org>" imported
gpg: key BB572E0E2D182910: 1 signature not checked due to a missing key
gpg: key BB572E0E2D182910: public key "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" imported
gpg: key A13D0EF1914E7A72: 1 signature not checked due to a missing key
gpg: key A13D0EF1914E7A72: public key "Gentoo repository mirrors (automated git signing key) <repomirrorci@gentoo.org>" imported
gpg: Total number processed: 4
gpg:               imported: 4
gpg: no ultimately trusted keys found

Next verify the cryptographic signature:

user $gpg --verify install-amd64-minimal-20240107T170309Z.iso.asc
gpg: assuming signed data in 'install-amd64-minimal-20240107T170309Z.iso'
gpg: Signature made Sun 07 Jan 2024 03:01:10 PM CST
gpg:                using RSA key 534E4209AB49EEE1C19D96162C44695DB9F6043D
gpg: Good signature from "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 13EB BDBE DE7A 1277 5DFD  B1BA BB57 2E0E 2D18 2910
     Subkey fingerprint: 534E 4209 AB49 EEE1 C19D  9616 2C44 695D B9F6 043D

To be absolutely certain that everything is valid, verify the fingerprint shown with the fingerprint on the Gentoo signatures page.

Note
It's generally good practice to mark an imported key as trusted, once it's certain the key is trustworthy. When trusted keys are verified, gpg will not say unknown and warn about the signature being untrusted.

Writing the boot media

Of course, with just an ISO file downloaded, the Gentoo Linux installation cannot be started. The ISO file must be written to bootable media. This generally requires that the image is extracted to a filesystem, or written directly to a device.

Writing a bootable USB

Most modern systems support booting from a USB device.

Writing with Linux

dd is typically available on most Linux distros, and can be used to write the Gentoo boot media to a USB drive.

Determining the USB device path

Before writing, the path to the desired storage device must be determined.

dmesg will display detailed information describing the storage device as it is added to the system:

root #dmesg
[268385.319745] sd 19:0:0:0: [sdd] 60628992 512-byte logical blocks: (31.0 GB/28.9 GiB)

Alternatively, lsblk can be used to display available storage devices:

root #lsblk
sdd           8:48   1  28.9G  0 disk
├─sdd1        8:49   1   246K  0 part
├─sdd2        8:50   1   2.8M  0 part
├─sdd3        8:51   1 463.5M  0 part
└─sdd4        8:52   1   300K  0 part

Once the device name has been determined, this can be added to the path prefix /dev/ to get the device path /dev/sdd.

Tip
Using the base device path, ie. sdd opposed to sdd1, is recommend as the Gentoo boot media contains a full GPT partition scheme.
Writing with dd
Warning
Be sure to check the target (of=target) path before executing dd, as it will be overwritten.

With the device path (/dev/sdd) and boot media install-amd64-minimal-<release timestamp>.iso ready:

root #dd if=install-amd64-minimal-<release timestamp>.iso of=/dev/sdd bs=4096 status=progress && sync
Note
if= specifies the input file, of= specifies the output file, which in this case, is a device.
Tip
bs=4096 is used as it speeds up transfers in most cases, status=progress displays transfers stats.

Burning a disk

See also
A more elaborate set of instructions can be found in CD/DVD/BD_writing#Image_writing.

Burning with Microsoft Windows 7 and above

Versions of Microsoft Windows 7 and above can both mount and burn ISO images to optical media without the requirement for third-party software. Simply insert a burnable disk, browse to the downloaded ISO files, right click the file in Windows Explorer, and select "Burn disk image".

Burning with Linux

The cdrecord utility from the package app-cdr/cdrtools can burn ISO images on Linux.

To burn the ISO file on the CD in the /dev/sr0 device (this is the first CD device on the system - substitute with the right device file if necessary):

user $cdrecord dev=/dev/sr0 install-amd64-minimal-20141204.iso

Users that prefer a graphical user interface can use K3B, part of the kde-apps/k3b package. In K3B, go to Tools and use Burn CD Image.

Booting

Booting the installation media

Once the installation media is ready, it is time to boot it. Insert the media in the system, reboot, and enter the motherboard's firmware user interface. This is usually performed by pressing a keyboard key such as DEL, F1, F10, or ESC during the Power-On Self-Test (POST) process. The 'trigger' key varies depending on the system and motherboard. If it is not obvious use an internet search engine and do some research using the motherboard's model name as the search keyword. Results should be easy to determine. Once inside the motherboard's firmware menu, change the boot order so that the external bootable media (CD/DVD disks or USB drives) are tried before the internal disk devices. Without this change, the system will most likely reboot to the internal disk device, ignoring the newly attached bootable media.

Important
When installing Gentoo on a system with an UEFI firmware interface, ensure the live image has been booted in UEFI mode. In the accidental event that DOS/legacy BIOS boot was initiated, then it will be necessary to reboot in UEFI mode before finalizing the Gentoo Linux installation.

Ensure that the installation media is inserted or plugged into the system, and reboot. A GRUB boot prompt should be shown with various boot entries. At this screen, Enter will begin the boot process with the default boot options. To boot the installation media with customized boot options, such as passing additional kernel parameters or the following hardware options, highlight a boot entry, then press the e key to edit the boot entry. Make the necessary modification(s), then press ctrl+x or F10 to boot the modified entry.

Note
In all likelihood, the default gentoo kernel, as mentioned above, without specifying any of the optional parameters will work just fine. For boot troubleshooting and expert options, continue on with this section. Otherwise, just press Enter and skip ahead to Extra hardware configuration.

At the boot prompt, users get the option of displaying the available kernels (F1) and boot options (F2). If no choice is made within 15 seconds (either displaying information or using a kernel) then the installation media will fall back to booting from disk. This allows installations to reboot and try out their installed environment without the need to remove the CD from the tray (something well appreciated for remote installations).

Specifying a kernel was mentioned. On the Minimal installation media, only two predefined kernel boot entries are provided. The default option is called gentoo. The other being the -nofb variant; this disables kernel framebuffer support.

The next section displays a short overview of the available kernels and their descriptions:

Kernel choices

gentoo
Default kernel with support for K8 CPUs (including NUMA support) and EM64T CPUs.
gentoo-nofb
Same as gentoo but without framebuffer support.
memtest86
Test the system RAM for errors.

Alongside the kernel, boot options help in tuning the boot process further.

Hardware options

acpi=on
This loads support for ACPI and also causes the acpid daemon to be started by the CD on boot. This is only needed if the system requires ACPI to function properly. This is not required for Hyperthreading support.
acpi=off
Completely disables ACPI. This is useful on some older systems and is also a requirement for using APM. This will disable any Hyperthreading support of your processor.
console=X
This sets up serial console access for the CD. The first option is the device, usually ttyS0, followed by any connection options, which are comma separated. The default options are 9600,8,n,1.
dmraid=X
This allows for passing options to the device-mapper RAID subsystem. Options should be encapsulated in quotes.
doapm
This loads APM driver support. This also requires that acpi=off.
dopcmcia
This loads support for PCMCIA and Cardbus hardware and also causes the pcmcia cardmgr to be started by the CD on boot. This is only required when booting from PCMCIA/Cardbus devices.
doscsi
This loads support for most SCSI controllers. This is also a requirement for booting most USB devices, as they use the SCSI subsystem of the kernel.
sda=stroke
This allows the user to partition the whole hard disk even when the BIOS is unable to handle large disks. This option is only used on machines with an older BIOS. Replace sda with the device that requires this option.
ide=nodma
This forces the disabling of DMA in the kernel and is required by some IDE chipsets and also by some CDROM drives. If the system is having trouble reading from the IDE CDROM, try this option. This also disables the default hdparm settings from being executed.
noapic
This disables the Advanced Programmable Interrupt Controller that is present on newer motherboards. It has been known to cause some problems on older hardware.
nodetect
This disables all of the autodetection done by the CD, including device autodetection and DHCP probing. This is useful for debugging a failing CD or driver.
nodhcp
This disables DHCP probing on detected network cards. This is useful on networks with only static addresses.
nodmraid
Disables support for device-mapper RAID, such as that used for on-board IDE/SATA RAID controllers.
nofirewire
This disables the loading of Firewire modules. This should only be necessary if your Firewire hardware is causing a problem with booting the CD.
nogpm
This disables gpm console mouse support.
nohotplug
This disables the loading of the hotplug and coldplug init scripts at boot. This is useful for debugging a failing CD or driver.
nokeymap
This disables the keymap selection used to select non-US keyboard layouts.
nolapic
This disables the local APIC on Uniprocessor kernels.
nosata
This disables the loading of Serial ATA modules. This is used if the system is having problems with the SATA subsystem.
nosmp
This disables SMP, or Symmetric Multiprocessing, on SMP-enabled kernels. This is useful for debugging SMP-related issues with certain drivers and motherboards.
nosound
This disables sound support and volume setting. This is useful for systems where sound support causes problems.
nousb
This disables the autoloading of USB modules. This is useful for debugging USB issues.
slowusb
This adds some extra pauses into the boot process for slow USB CDROMs, like in the IBM BladeCenter.

Logical volume/device management

dolvm
This enables support for Linux's Logical Volume Management.

Other options

debug
Enables debugging code. This might get messy, as it displays a lot of data to the screen.
docache
This caches the entire runtime portion of the CD into RAM, which allows the user to umount /mnt/cdrom and mount another CDROM. This option requires that there is at least twice as much available RAM as the size of the CD.
doload=X
This causes the initial ramdisk to load any module listed, as well as dependencies. Replace X with the module name. Multiple modules can be specified by a comma-separated list.
dosshd
Starts sshd on boot, which is useful for unattended installs.
passwd=foo
Sets whatever follows the equals as the root password, which is required for dosshd since the root password is by default scrambled.
noload=X
This causes the initial ramdisk to skip the loading of a specific module that may be causing a problem. Syntax matches that of doload.
nonfs
Disables the starting of portmap/nfsmount on boot.
nox
This causes an X-enabled LiveCD to not automatically start X, but rather, to drop to the command line instead.
scandelay
This causes the CD to pause for 10 seconds during certain portions the boot process to allow for devices that are slow to initialize to be ready for use.
scandelay=X
This allows the user to specify a given delay, in seconds, to be added to certain portions of the boot process to allow for devices that are slow to initialize to be ready for use. Replace X with the number of seconds to pause.
Note
The bootable media will check for no* options before do* options, so that options can be overridden in the exact order specified.

Now boot the media, select a kernel (if the default gentoo kernel does not suffice) and boot options. As an example, we boot the gentoo kernel, with dopcmcia as a kernel parameter:

boot:gentoo dopcmcia

Next the user will be greeted with a boot screen and progress bar. If the installation is done on a system with a non-US keyboard, make sure to immediately press Alt+F1 to switch to verbose mode and follow the prompt. If no selection is made in 10 seconds the default (US keyboard) will be accepted and the boot process will continue. Once the boot process completes, the user is automatically logged in to the "Live" Gentoo Linux environment as the root user, the super user. A root prompt is displayed on the current console, and one can switch to other consoles by pressing Alt+F2, Alt+F3 and Alt+F4. Get back to the one started on by pressing Alt+F1.


Extra hardware configuration

When the Installation medium boots, it tries to detect all the hardware devices and loads the appropriate kernel modules to support the hardware. In the vast majority of cases, it does a very good job. However, in some cases it may not auto-load the kernel modules needed by the system. If the PCI auto-detection missed some of the system's hardware, the appropriate kernel modules have to be loaded manually.

In the next example the 8139too module (which supports certain kinds of network interfaces) is loaded:

root #modprobe 8139too

Optional: User accounts

If other people need access to the installation environment, or there is need to run commands as a non-root user on the installation medium (such as to chat using irssi without root privileges for security reasons), then an additional user account needs to be created and the root password set to a strong password.

To change the root password, use the passwd utility:

root #passwd
New password: (Enter the new password)
Re-enter password: (Re-enter the password)

To create a user account, first enter their credentials, followed by the account's password. The useradd and passwd commands are used for these tasks.

In the next example, a user called john is created:

root #useradd -m -G users john
root #passwd john
New password: (Enter john's password)
Re-enter password: (Re-enter john's password)

To switch from the (current) root user to the newly created user account, use the su command:

root #su - john

Optional: Viewing documentation while installing

TTYs

To view the Gentoo handbook from a TTY during the installation, first create a user account as described above, then press Alt+F2 to go to a new terminal (TTY) and login as the newly created user. Following the principle of least privilege, it is best practice to avoid browsing the web or generally performing any task with higher privileges than necessary. The root account has full control of the system and therefore must be used sparingly.

During the installation, the links web browser can be used to browse the Gentoo handbook - of course only from the moment that the Internet connection is working.

user $links https://wiki.gentoo.org/wiki/Handbook:AMD64

To go back to the original terminal, press Alt+F1.

Tip
When booted to the Gentoo minimal or Gentoo admin environments, seven TTYs will be available. They can be switched by pressing Alt then a function key between F1-F7. It can be useful to switch to a new terminal when waiting for job to complete, to open documentation, etc.

GNU Screen

The Screen utility is installed by default on official Gentoo installation media. It may be more efficient for the seasoned Linux enthusiast to use screen to view installation instructions via split panes rather than the multiple TTY method mentioned above.

Optional: Starting the SSH daemon

To allow other users to access the system during the installation (perhaps to provide/receive support during an installation, or even do it remotely), a user account needs to be created (as was documented earlier on) and the SSH daemon needs to be started.

To fire up the SSH daemon on an OpenRC init, execute the following command:

root #rc-service sshd start
Note
If users log on to the system, they will see a message that the host key for this system needs to be confirmed (through what is called a fingerprint). This behavior is typical and can be expected for initial connections to an SSH server. However, later when the system is set up and someone logs on to the newly created system, the SSH client will warn that the host key has been changed. This is because the user now logs on to - for SSH - a different server (namely the freshly installed Gentoo system rather than the live environment that the installation is currently using). Follow the instructions given on the screen then to replace the host key on the client system.

To be able to use sshd, the network needs to function properly. Continue with the chapter on Configuring the network.





Automatic network configuration

Maybe it just works?

If the system is connected to an Ethernet network with an IPv6 router or DHCP server, it's very likely that the system's network was configured automatically. If additional, advanced configuration is not required, Internet connectivity can be tested.

Using DHCP

DHCP (Dynamic Host Configuration Protocol) assists in network configuration, and can automatically provide configuration for a variety of parameters including: IP address, network mask, routes, DNS servers, NTP servers, etc.

DHCP requires that a server be running on the same Layer 2 (Ethernet) segment as the client requesting a lease. DHCP is often used on RFC1918 (private) networks, but is also used to acquire public IP information from ISPs.

Tip
Official Gentoo boot media runs dhcpcd automatically at startup. This behavior can be disabled by adding the nodhcp argument to the boot media kernel commandline.

If it is not already running, dhcpcd can be started on enp1s0 with:

root #dhcpcd enp1s0

Some network administrators require that the hostname and domain name provided by the DHCP server is used by the system. In that case, use:

root #dhcpcd -HD enp1s0

To stop dhcpcd, -x can be used:

root #dhcpcd -x
sending signal Term to pid 10831
waiting for pid 10831 to exit
See also
Dhcpcd usage

Testing the network

A properly configured default route is a critical component of Internet connectivity, route configuration can be checked with:

root #ip route
default via 192.168.0.1 dev enp1s0

If no default route is defined, Internet connectivity is unavailable, and additional configuration is required.

Basic internet connectivity can be confirmed with a ping:

root #ping -c 3 1.1.1.1
Tip
It's helpful to start by pinging a known IP address instead of a hostname. This can isolate DNS issues from basic Internet connectivity issues.

Outbound HTTPS access and DNS resolution can be confirmed with:

root #curl --location gentoo.org --output /dev/null

Unless curl reports an error, or other tests fail, the installation process can be continued with disk preparation.

If curl reports an error, but Internet-bound pings work, DNS may need configuration.

If Internet connectivity has not been established, first interface information should be verified, then:

Obtaining interface info

If networking doesn't work out of the box, additional steps must be taken to enable Internet connectivity. Generally, the first step is to enumerate host network interfaces.

The ip command, part of the sys-apps/iproute2 package, can be used to query and configure system networking.

The link argument can be used to display network interface links:

root #ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
4: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether e8:40:f2:ac:25:7a brd ff:ff:ff:ff:ff:ff

The address argument can be used to query device address information:

root #ip address
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether e8:40:f2:ac:25:7a brd ff:ff:ff:ff:ff:ff
    inet 10.0.20.77/22 brd 10.0.23.255 scope global enp1s0
       valid_lft forever preferred_lft forever
    inet6 fe80::ea40:f2ff:feac:257a/64 scope link 
       valid_lft forever preferred_lft forever

The output of this command contains information for each network interface on the system. Entries begin with the device index, followed by the device name: enp1s0.

Tip
If no interfaces other than the lo (loopack) are displayed, then the networking hardware is faulty, or the driver for the interface has not been loaded into the kernel. Both situations reach beyond the scope of this Handbook. Please ask for support in contact #gentoo (webchat).

For consistency, the handbook will assume that the primary network interface is called enp1s0.

Note
As a result of the shift toward predictable network interface names, the interface name on the system can be quite different than the old eth0 naming convention. Modern Gentoo boot media uses interface names with prefixes such as eno0, ens1, or enp5s0.

Optional: Application specific configuration

The following methods are not generally required, but may be helpful in situations where additional configuration is required for Internet connectivity.

Configure web proxies

If the internet is accessed through a web proxy, then it will be necessary to define proxy information to for Portage to properly access the proxy for each supported protocol. Portage observes the http_proxy, ftp_proxy, and RSYNC_PROXY environment variables in order to download packages via its wget and rsync retrieval mechanisms.

Certain text-mode web browsers such as links can also make use of environment variables that define web proxy settings; in particular for the HTTPS access it also will require the https_proxy environment variable to be defined. While Portage will be influenced without passing extra run time parameters during invocation, links will require proxy settings to be set.

In most cases, it is sufficient to define environment variables using the server hostname. In the following example, it is assumed the proxy server host is called proxy.gentoo.org and the port is 8080.

Note
The # symbol in the following commands is a comment. It has een added for clarity only and does not need to be typed when entering the commands.

To define an HTTP proxy (for HTTP and HTTPS traffic):

root #export http_proxy="http://proxy.gentoo.org:8080" # Applies to Portage and Links
root #export https_proxy="http://proxy.gentoo.org:8080" # Only applies for Links

If the HTTP proxy requires authentication, set a username and password with the following syntax:

root #export http_proxy="http://username:password@proxy.gentoo.org:8080" # Applies to Portage and Links
root #export https_proxy="http://username:password@proxy.gentoo.org:8080" # Only applies for Links

Start links using the following parameters for proxy support:

user $links -http-proxy ${http_proxy} -https-proxy ${https_proxy}

To define an FTP proxy for Portage and/or links:

root #export ftp_proxy="ftp://proxy.gentoo.org:8080" # Applies to Portage and Links

Start links using the following parameter for a FTP proxy:

user $links -ftp-proxy ${ftp_proxy}

To define an RSYNC proxy for Portage:

root #export RSYNC_PROXY="proxy.gentoo.org:8080" # Applies to Portage; Links does not support a rsync proxy

Using pppoe-setup for ADSL

If PPPoE is required for Internet access, the Gentoo boot media includes the pppoe-setup script to simplify ppp configuration.

During setup, pppoe-setup will ask for:

  • The name of the Ethernet interface connected to the ADSL modem.
  • The PPPoE username and password.
  • DNS server IPs.
  • Whether or not a firewall is needed.
root #pppoe-setup
root #pppoe-start

In the event of failure, credentials in /etc/ppp/pap-secrets or /etc/ppp/chap-secrets should be verified. If credentials are correct, PPPoE Ethernet interface selection should be checked.

Using PPTP

If PPTP support is needed, pptpclient can be used, but requires configuration prior to usage.

Edit /etc/ppp/pap-secrets or /etc/ppp/chap-secrets so it contains the correct username/password combination:

root #nano /etc/ppp/chap-secrets

Then adjust /etc/ppp/options.pptp if necessary:

root #nano /etc/ppp/options.pptp

Once configuration is complete, run pptp (along with the options that couldn't be set in options.pptp) to connect the server:

root #pptp <server ipv4 address>

Configuring WEP

Warning
Do not use WEP unless it is the only option. WEP provides essentially no security over an open network.
Important
The iw command is only available on the following architectures: amd64, x86, arm, arm64, ppc, ppc64, and riscv.

When using a wireless (802.11) card, the wireless settings need to be configured before going any further. To see the current wireless settings on the card, one can use iw. Running iw might show something like:

root #iw dev wlp9s0 info
Interface wlp9s0
	ifindex 3
	wdev 0x1
	addr 00:00:00:00:00:00
	type managed
	wiphy 0
	channel 11 (2462 MHz), width: 20 MHz (no HT), center1: 2462 MHz
	txpower 30.00 dBm

To check for a current connection:

root #iw dev wlp9s0 link
Not connected.

or

root #iw dev wlp9s0 link
Connected to 00:00:00:00:00:00 (on wlp9s0)
	SSID: GentooNode
	freq: 2462
	RX: 3279 bytes (25 packets)
	TX: 1049 bytes (7 packets)
	signal: -23 dBm
	tx bitrate: 1.0 MBit/s
Note
Some wireless cards may have a device name of wlan0 or ra0 instead of wlp9s0. Run ip link to determine the correct device name.

For most users, there are only two settings needed to connect, the ESSID (aka wireless network name) and, optionally, the WEP key.

  • First, ensure the interface is active:
root #ip link set dev wlp9s0 up
  • To connect to an open network with the name GentooNode:
root #iw dev wlp9s0 connect -w GentooNode
  • To connect with a hex WEP key, prefix the key with d::
root #iw dev wlp9s0 connect -w GentooNode key 0:d:1234123412341234abcd
  • To connect with an ASCII WEP key:
root #iw dev wlp9s0 connect -w GentooNode key 0:some-password
Note
If the wireless network is set up with WPA or WPA2, then wpa_supplicant needs to be used. For more information on configuring wireless networking in Gentoo Linux, please read the Wireless networking chapter in the Gentoo Handbook.

Confirm the wireless settings by using iw dev wlp9s0 link. Once wireless is working, continue configuring the IP level networking options as described in the next section (Understanding network terminology) or use the net-setup tool as described previously.

Using net-setup

In cases where automatic network configuration is unsuccessful, the Gentoo boot media provides scripts to aid in network configuration. net-setup can be used to configure wireless network information and static IPs.

root #net-setup enp1s0

net-setup will ask some questions about the network environment and will use that information to configure wpa_supplicant or static addressing.

Important
Network status should be tested after any configuration steps are taken. In the event that configuration scripts do not work, manual network configuration is required.

Internet and IP basics

If all of the above fails, the network must be configured manually. This is not particularly difficult, but should be done with consideration. This section serves to clarify terminology and introduce users to basic networking concepts pertaining to manually configuring an Internet connection.

Tip
Some CPE (Carrier Provided Equipment) combines the functions of a router, access point, modem, DHCP server, and DNS server into one unit. It's important to differentiate the functions of a device from the physical appliance.

Interfaces and addresses

Network interfaces are logical representations of network devices. An interface needs an address to communicate with other devices on the network. While only a single address is required, multiple addresses can be assigned to a single interface. This is especially useful for dual stack (IPv4 + IPv6) configurations.

For consistency, this primer will assume the interface enp1s0 will be using the address 192.168.0.2.

Important
IP addresses can be set arbitrarily. As a result, it's possible for multiple devices to use the same IP address, resulting in an address conflict. Address conflicts should be avoided by using DHCP or SLAAC.
Tip
IPv6 typically uses StateLess Address AutoConfiguration (SLAAC) for address configuration. In most cases, manually setting IPv6 addresses is a bad practice. If a specific address suffix is preferred, interface identification tokens can be used.

Networks and CIDR

Once an address is chosen, how does a device know how to talk to other devices?

IP addresses are associated with networks. IP networks are contiguous logical ranges of addresses.

Classless Inter-Domain Routing or CIDR notation is used to distinguish network sizes.

  • The CIDR value, often notated starting with a /, represents the size of the network.
    • The formula 2 ^ (32 - CIDR) can be used to calculate network size.
    • Once network size is calculated, usable node count must be reduced by 2.
      • The first IP in a network is the Network address, and the last is typically the Broadcast address. These addresses are special and cannot be used by normal hosts.
Tip
The most common CIDR values are /24, and /32, representing 254 nodes and a single node respectively.

A CIDR of /24 is the de-facto default network size. This corresponds to a subnet mask of 255.255.255.0, where the last 8 bits are reserved for IP addresses for nodes on a network.

The notation: 192.168.0.2/24 can be interpreted as:

  • The address 192.168.0.2
  • On the network 192.168.0.0
  • With a size of 254 (2 ^ (32 - 24) - 2)
    • Usable IPs are in the range 192.168.0.1 - 192.168.0.254
  • With a broadcast address of 192.168.0.255
    • In most cases, the last address on a network is used as the broadcast address, but this can be changed.

Using this configuration, a device should be able to communicate with any host on the same network (192.168.0.0).

The Internet

Once a device is on a network, how does it know how to talk to devices on the Internet?

To communicate with devices outside of local networks, routing must be used. A router is simply a network device that forwards traffic for other devices. The term default route or gateway typically refers to whatever device on the current network is used for external network access.

Tip
It's a standard practice to make the gateway the first or last IP on a network.

If an Internet-connected router is available at 192.168.0.1, it can be used as the default route, granting Internet access.

To summarize:

  • Interfaces must be configured with an address and network information, such as the CIDR value.
  • Local network access is used to access a router on the same network.
  • The default route is configured, so traffic destined for external networks is forwarded to the gateway, providing Internet access.

The Domain Name System

Remembering IPs is hard. The Domain Name System was created to allow mapping between Domain Names and IP addresses.

Linux systems use /etc/resolv.conf to define nameservers to be used for DNS resolution.

Tip
Many routers can also function as a DNS server, and using a local DNS server can augment privacy and speed up queries through caching.

Many ISPs run a DNS server that is generally advertised to the gateway over DHCP. Using a local DNS server tends to improve query latency, but most public DNS servers will return the same results, so server usage is largely based on preference.

Manual network configuration

Interface address configuration

Important
When manually configuring IP addresses, the local network topology must be considered. IP addresses can be set arbitrarily; conflicts may cause network disruption.

To configure enp1s0 with the address 192.168.0.2 and CIDR /24:

root #ip address add 192.168.0.2/24 dev enp1s0
Tip
The start of this command can be shortened to ip a.

Default route configuration

Configuring address and network information for an interface will configure link routes, allowing communication with that network segment:

root #ip route
192.168.0.0/24 dev enp1s0 proto kernel scope link src 192.168.0.2
Tip
This command can be shortened to ip r.

The default route can be set to 192.168.0.1 with:

root #ip route add default via 192.168.0.1

DNS configuration

Nameserver info is typically acquired using DHCP, but can be set manually by adding nameserver entries to /etc/resolv.conf.

Warning
If dhcpcd is running, changes to /etc/resolv.conf will not persist. Status can be checked with ps x | grep dhcpcd.

nano is included in Gentoo boot media and can be used to edit /etc/resolv.conf with:

root #nano /etc/resolv.conf

Lines containing the keyword nameserver followed by a DNS server IP address are queried in order of definition:

FILE /etc/resolv.confUse Quad9 DNS.
nameserver 9.9.9.9
nameserver 149.112.112.112
FILE /etc/resolv.confUse Cloudflare DNS.
nameserver 1.1.1.1
nameserver 1.0.0.1

DNS status can be checked by pinging a domain name:

root #ping -c 3 gentoo.org

Once connectivity has been verified, continue with Preparing the disks.





Introduction to block devices

Block devices

Let's take a good look at disk-oriented aspects of Gentoo Linux and Linux in general, including block devices, partitions, and Linux filesystems. Once the ins and outs of disks are understood, partitions and filesystems can be established for installation.

To begin, let's look at block devices. SCSI and Serial ATA drives are both labeled under device handles such as: /dev/sda, /dev/sdb, /dev/sdc, etc. On more modern machines, PCI Express based NVMe solid state disks have device handles such as /dev/nvme0n1, /dev/nvme0n2, etc.

The following table will help readers determine where to find a certain type of block device on the system:

Type of device Default device handle Editorial notes and considerations
IDE, SATA, SAS, SCSI, or USB flash /dev/sda Found on hardware from roughly 2007 until the present, this device handle is perhaps the most commonly used in Linux. These types of devices can be connected via the SATA bus, SCSI, USB bus as block storage. As example, the first partition on the first SATA device is called /dev/sda1.
NVM Express (NVMe) /dev/nvme0n1 The latest in solid state technology, NVMe drives are connected to the PCI Express bus and have the fastest transfer block speeds on the market. Systems from around 2014 and newer may have support for NVMe hardware. The first partition on the first NVMe device is called /dev/nvme0n1p1.
MMC, eMMC, and SD /dev/mmcblk0 embedded MMC devices, SD cards, and other types of memory cards can be useful for data storage. That said, many systems may not permit booting from these types of devices. It is suggested to not use these devices for active Linux installations; rather consider using them to transfer files, which is their typical design intention. Alternatively this storage type could be useful for short-term file backups or snapshots.

The block devices above represent an abstract interface to the disk. User programs can use these block devices to interact with the disk without worrying about whether the drives are SATA, SCSI, or something else. The program can simply address the storage on the disk as a bunch of contiguous, randomly-accessible 4096-byte (4K) blocks.


Partition tables

Although it is theoretically possible to use a raw, unpartitioned disk to house a Linux system (when creating a btrfs RAID for example), this is almost never done in practice. Instead, disk block devices are split up into smaller, more manageable block devices. On amd64 systems, these are called partitions. There are currently two standard partitioning technologies in use: MBR (sometimes also called DOS disklabel) and GPT; these are tied to the two boot process types: legacy BIOS boot and UEFI.

GUID Partition Table (GPT)

The GUID Partition Table (GPT) setup (also called GPT disklabel) uses 64-bit identifiers for the partitions. The location in which it stores the partition information is much bigger than the 512 bytes of the MBR partition table (DOS disklabel), which means there is practically no limit on the number of partitions for a GPT disk. Also, the maximum partition size is much larger (almost 8 ZiB -- yes, zettabytes).

When a system's software interface between the operating system and firmware is UEFI (instead of BIOS), GPT is almost mandatory as compatibility issues will arise with DOS disklabel.

GPT also takes advantage of checksumming and redundancy. It carries CRC32 checksums to detect errors in the header and partition tables and has a backup GPT at the end of the disk. This backup table can be used to recover damage of the primary GPT near the beginning of the disk.

Important
There are a few caveats regarding GPT:
  • Using GPT on a BIOS-based computer works, but the user won't be able to dual-boot with a Microsoft Windows operating system, since Microsoft Windows refuses to boot from a GPT partition when in BIOS mode.
  • Some buggy (old) motherboard firmware configured to boot in BIOS/CSM/legacy mode might also have problems with booting from GPT labeled disks.

Master boot record (MBR) or DOS boot sector

The Master boot record boot sector (also called DOS boot sector, DOS disklabel, and - more recently, in contrast to GPT/UEFI setups - legacy BIOS boot) was first introduced in 1983 with PC DOS 2.x. MBR uses 32-bit identifiers for the start sector and length of the partitions, and supports three partition types: primary, extended, and logical. Primary partitions have their information stored in the master boot record itself - a very small (usually 512 bytes) location at the very beginning of a disk. Due to this small space, only four primary partitions are supported (for instance, /dev/sda1 to /dev/sda4).

In order to support more partitions, one of the primary partitions in the MBR can be marked as an extended partition. This partition can then contain additional logical partitions (partitions within a partition).

Important
Although still supported by most motherboard manufacturers, MBR boot sectors and their associated partitioning limitations are considered legacy. Unless working with hardware that is pre-2010, it best to partition a disk with GUID Partition Table. Readers who must proceed with setup type should knowingly acknowledge the following information:
  • Most post-2010 motherboards consider using MBR boot sectors a legacy (supported, but not ideal) boot mode.
  • Due to using 32-bit identifiers, partition tables in the MBR cannot address storage space that is larger than 2 TiBs in size.
  • Unless an extended partition is created, MBR supports a maximum of four partitions.
  • This setup does not provide a backup boot sector, so if something overwrites the partition table, all partition information will be lost.
That said, MBR and legacy BIOS boot may still used in virtualized cloud environments such as AWS.

The Handbook authors suggest using GPT whenever possible for Gentoo installations.

Advanced storage

The official Gentoo boot media provides support for Logical Volume Manager (LVM). LVM can combine physical volumes such as partitions or disks into volume groups. Volume groups are more flexible than partitions and can be used to define RAID groups or caches on fast SSDs for slow HDs. Although usage is not covered in the handbook, LVM is fully supported in Gentoo.

Default partitioning scheme

Throughout the remainder of the handbook, we will discuss and explain two cases:

  1. UEFI firmware with GUID Partition Table (GPT) disk.
  2. MBR DOS/legacy BIOS firmware with a MBR partition table disk.

While it is possible to mix and match boot types with certain motherboard firmware, mixing goes beyond the intention of the handbook. As previously stated, it is strongly recommended for installations on modern hardware to use UEFI boot with a GPT disklabel disk.

The following partitioning scheme will be used as a simple example layout.

Important
The first row of the following table contains exclusive information for either a GPT disklabel or a MBR DOS/legacy BIOS disklabel. When in doubt, proceed with GPT, since amd64 machines manufactured after the year 2010 generally support UEFI firmware and GPT boot sector.
Partition Filesystem Size Description
/dev/sda1 fat32 File system required for the EFI System Partition, which is always associated with a GPT disklabel. 1 GiB EFI System Partition details. Applicable to system firmware supporting an UEFI implementation. This is typically the case for systems manufactured around the year 2010 to the present.
xfs Recommended file system for the boot partition of a MBR partition table, which is used in conjunction with older firmware limited to the DOS/legacy BIOS disklabel. MBR DOS/legacy BIOS boot partition details. Applicable to legacy BIOS machine firmware. Systems of this type were typically manufactured <u>before</u> the year 2010 and have generally phased out of production.
/dev/sda2 linux-swap RAM size * 2 Swap partition details.
/dev/sda3 xfs Remainder of the disk The selected profile, additional partitions (optional), and system purpose add complexities for appropriately sizing the rootfs, therefore the Handbook authors cannot offer a 'one-size-fits-all' suggestion for the rootfs partition.</br></br> When Gentoo is the only operating system using the disk, selecting the remainder of the disk is the safest and suggested choice. Root partition details.

If this suffices as information, the advanced reader can directly skip ahead to the actual partitioning.

Both fdisk and parted are partitioning utilities included within the official Gentoo live image environments. fdisk is well known, stable, and handles both MBR and GPT disks. parted was one of the first Linux block device management utilities to support GPT partitions. It can be used as an alternative to fdisk if the reader prefers, however the handbook will only provide instructions for fdisk, since since it is commonly available on most Linux environments.

Before going to the creation instructions, the first set of sections will describe in more detail how partitioning schemes can be created and mention some common pitfalls.


Designing a partition scheme

How many partitions and how big?

The design of disk partition layout is highly dependent on the demands of the system and the file system(s) applied to the device. If there are lots of users, then it is advised to have /home on a separate partition which will increase security and make backups and other types of maintenance easier. If Gentoo is being installed to perform as a mail server, then /var should be a separate partition as all mails are stored inside the /var directory. Game servers may have a separate /opt partition since most gaming server software is installed therein. The reason for these recommendations is similar to the /home directory: security, backups, and maintenance.

In most situations on Gentoo, /usr and /var should be kept relatively large in size. /usr hosts the majority of applications available on the system and the Linux kernel sources (under /usr/src). By default, /var hosts the Gentoo ebuild repository (located at /var/db/repos/gentoo) which, depending on the file system, generally consumes around 650 MiB of disk space. This space estimate excludes the /var/cache/distfiles and /var/cache/binpkgs directories, which will gradually fill with source files and (optionally) binary packages respectively as they are added to the system.

How many partitions and how big very much depends on considering the trade-offs and choosing the best option for the circumstance. Separate partitions or volumes have the following advantages:

  • Choose the best performing filesystem for each partition or volume.
  • The entire system cannot run out of free space if one defunct tool is continuously writing files to a partition or volume.
  • If necessary, file system checks are reduced in time, as multiple checks can be done in parallel (although this advantage is realized more with multiple disks than it is with multiple partitions).
  • Security can be enhanced by mounting some partitions or volumes read-only, nosuid (setuid bits are ignored), noexec (executable bits are ignored), etc.


However, multiple partitions have certain disadvantages as well:

  • If not configured properly, the system might have lots of free space on one partition and little free space on another.
  • A separate partition for /usr/ may require the administrator to boot with an initramfs to mount the partition before other boot scripts start. Since the generation and maintenance of an initramfs is beyond the scope of this handbook, we recommend that newcomers do not use a separate partition for /usr/.
  • There is also a 15-partition limit for SCSI and SATA unless the disk uses GPT labels.
Note
Installations that intend to use systemd as the service and init system must have the /usr directory available at boot, either as part of the root filesystem or mounted via an initramfs.

What about swap space?

Recommendations for swap space size
RAM size Suspend support? Hibernation support?
2 GB or less 2 * RAM 3 * RAM
2 to 8 GB RAM amount 2 * RAM
8 to 64 GB 8 GB minimum, 16 maximum 1.5 * RAM
64 GB or greater 8 GB minimum Hibernation not recommended! Hibernation is not recommended for systems with very large amounts of memory. While possible, the entire contents of memory must be written to disk in order to successfully hibernate. Writing tens of gigabytes (or worse!) out to disk can can take a considerable amount of time, especially when rotational disks are used. It is best to suspend in this scenario.

There is no perfect value for swap space size. The purpose of the space is to provide disk storage to the kernel when internal dynamic memory (RAM) is under pressure. A swap space allows for the kernel to move memory pages that are not likely to be accessed soon to disk (swap or page-out), which will free memory in RAM for the current task. Of course, if the pages swapped to disk are suddenly needed, they will need to be put back in memory (page-in) which will take considerably longer than reading from RAM (as disks are very slow compared to internal memory).

When a system is not going to run memory intensive applications or has lots of RAM available, then it probably does not need much swap space. However do note in case of hibernation that swap space is used to store the entire contents of memory (likely on desktop and laptop systems rather than on server systems). If the system requires support for hibernation, then swap space larger than or equal to the amount of memory is necessary.

As a general rule for RAM amounts less than 4 GB, the swap space size is recommended to be twice the internal memory (RAM). For systems with multiple hard disks, it is wise to create one swap partition on each disk so that they can be utilized for parallel read/write operations. The faster a disk can swap, the faster the system will run when data in swap space must be accessed. When choosing between rotational and solid state disks, it is better for performance to put swap on the solid state hardware.

It is worth noting that swap files can be used as an alternative to swap partitions; this is mostly helpful for systems with very limited disk space.


What is the EFI System Partition (ESP)?

When installing Gentoo on a system that uses UEFI to boot the operating system (instead of BIOS) it is essential that an EFI System Partition (ESP) is created. The instructions below contain the necessary pointers to correctly handle this operation. The EFI system partition is not required when booting in BIOS/Legacy mode.

The ESP must be a FAT variant (sometimes shown as vfat on Linux systems). The official UEFI specification denotes FAT12, 16, or 32 filesystems will be recognized by the UEFI firmware, although FAT32 is recommended for the ESP. After partitioning, format the ESP accordingly:

root #mkfs.fat -F 32 /dev/sda1
Important
If the ESP is not formatted with a FAT variant, the system's UEFI firmware will not find the bootloader (or Linux kernel) and will most likely be unable to boot the system!

What is the BIOS boot partition?

A BIOS boot partition is a very small (1 to 2 MB) partition in which boot loaders like GRUB2 can put additional data that doesn't fit in the allocated storage. It only needed when a disk is formatted with a GPT disklabel, but the system's firmware will be booting via GRUB2 in legacy BIOS/MBR DOS boot mode. It is not required when booting in EFI/UEFI mode, and also not required when using a MBR/Legacy DOS disklabel. A BIOS boot partition will not be used in this guide.

Partitioning the disk with GPT for UEFI

The following parts explain how to create an example partition layout for a single GPT disk device which will conform to the UEFI Specification and Discoverable Partitions Specification (DPS). DPS is a specification provided as part of the Linux Userspace API (UAPI) Group Specification and is recommended, but entirely optional. The specifications are implemented using the fdisk utility, which is part of the sys-apps/util-linux package.

The table provides a recommended defaults for a trivial Gentoo installation. Additional partitions can be added according to personal preference or system design goals.

Device path (sysfs) Mount point File system DPS UUID (Type-UUID) Description
/dev/sda1 /efi vfat c12a7328-f81f-11d2-ba4b-00a0c93ec93b EFI system partition (ESP) details.
/dev/sda2 N/A. Swap is not mounted to the filesystem like a device file. swap 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f Swap partition details.
/dev/sda3 / xfs 4f68bce3-e8cd-4db1-96e7-fbcaf984b709 Root partition details.

Viewing the current partition layout

fdisk is a popular and powerful tool to split a disk into partitions. Fire up fdisk against the disk (in our example, we use /dev/sda):

root #fdisk /dev/sda

Use the p key to display the disk's current partition configuration:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 3E56EE74-0571-462B-A992-9872E3855D75

Device        Start        End    Sectors   Size Type
/dev/sda1      2048    2099199    2097152     1G EFI System
/dev/sda2   2099200   10487807    8388608     4G Linux swap
/dev/sda3  10487808 1953523711 1943035904 926.5G Linux root (x86-64)

This particular disk was configured to house two Linux filesystems (each with a corresponding partition listed as "Linux") as well as a swap partition (listed as "Linux swap").

Creating a new disklabel / removing all partitions

Pressing the g key will instantly remove all existing disk partitions and create a new GPT disklabel:

Command (m for help):g
Created a new GPT disklabel (GUID: 3E56EE74-0571-462B-A992-9872E3855D75).

Alternatively, to keep an existing GPT disklabel (see the output of p above), consider removing the existing partitions one by one from the disk. Press d to delete a partition. For instance, to delete an existing /dev/sda1:

Command (m for help):d
Partition number (1-4): 1

The partition has now been scheduled for deletion. It will no longer show up when printing the list of partitions (p, but it will not be erased until the changes have been saved. This allows users to abort the operation if a mistake was made - in that case, press q immediately and hit Enter and the partition will not be deleted.

Repeatedly press p to print out a partition listing and then press d and the number of the partition to delete it. Eventually, the partition table will be empty:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 3E56EE74-0571-462B-A992-9872E3855D75

Now that the in-memory partition table is empty, we're ready to create the partitions.

Creating the EFI System Partition (ESP)

Note
A smaller ESP is possible but not recommended, especially given it may be shared with other OSes.

First create a small EFI system partition, which will also be mounted as /boot. Type n to create a new partition, followed by 1 to select the first partition. When prompted for the first sector, make sure it starts from 2048 (which may be needed for the boot loader) and hit Enter. When prompted for the last sector, type +1G to create a partition 1 GByte in size:

Command (m for help):n
Partition number (1-128, default 1): 1
First sector (2048-1953525134, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-1953525134, default 1953523711): +1G
 
Created a new partition 1 of type 'Linux filesystem' and of size 1 GiB.
Partition #1 contains a vfat signature.

Do you want to remove the signature? [Y]es/[N]o: Y
The signature will be removed by a write command.

Mark the partition as an EFI system partition:

Command (m for help):t
Selected partition 1
Partition type or alias (type L to list all): 1
Changed type of partition 'Linux filesystem' to 'EFI System'.

Optionally, to have the ESP conform to the Discoverable System Partition (DSP) specification, switch to expert mode and perform the following extra step to set the partition's UUID:

Command (m for help):x
Expert command (m for help):u
Selected partition 1

New UUID (in 8-4-4-4-12 format): c12a7328-f81f-11d2-ba4b-00a0c93ec93b
Partition UUID changed from 10293DC1-DF6C-4443-8ACF-C756B81B4767 to C12A7328-F81F-11D2-BA4B-00A0C93EC93B.

Press the r key to return to the main menu:

Expert command (m for help):r

Command (m for help):

Creating the swap partition

Next, to create the swap partition, press n to create a new partition, then press 2 to create the second partition, /dev/sda2. When prompted for the first sector, hit Enter. When prompted for the last sector, type +4G (or any other size needed for the swap space) to create a partition 4 GiB in size.

Command (m for help):n
Partition number (2-128, default 2): 
First sector (2099200-1953525134, default 2099200): 
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2099200-1953525134, default 1953523711): +4G
 
Created a new partition 2 of type 'Linux filesystem' and of size 4 GiB.

After this, press t to set the partition type, 2 to select the partition just created and then type in 19 to set the partition type to "Linux Swap".

Command (m for help):t
Partition number (1,2, default 2): 2
Partition type or alias (type L to list all): 19
 
Changed type of partition 'Linux filesystem' to 'Linux swap'.

Optionally, to have the swap partition conform to the Discoverable System Partition (DSP) specification, switch to expert mode and perform the following extra step to set the partition's UUID:

Command (m for help):x
Expert command (m for help):u
Partition number (1,2, default 2): 2
Selected partition 2

New UUID (in 8-4-4-4-12 format): 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
Partition UUID changed from 7529CDF6-9482-4497-B021-576745648B2A to 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F..

Press the r key to return to the main menu:

Expert command (m for help):r

Command (m for help):

Creating the root partition

Finally, to create the root partition, press n to create a new partition, and then press 3 to create the third partition: /dev/sda3. When prompted for the first sector, press Enter. When prompted for the last sector, hit Enter to create a partition that takes up the rest of the remaining space on the disk.

Command (m for help):n
Partition number (3-128, default 3): 3
First sector (10487808-1953525134, default 10487808):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (10487808-1953525134, default 1953523711):

Created a new partition 3 of type 'Linux filesystem' and of size 926.5 GiB..
Note
Setting the root partition's type to "Linux root (x86-64)" is not required and the system will function normally if it is set to the "Linux filesystem" type. This filesystem type is only necessary for cases where a bootloader that supports it (i.e. systemd-boot) is used and a fstab file is not wanted.

After creating the root partition, press t to set the partition type, 3 to select the partition just created, and then type in 23 to set the partition type to "Linux Root (x86-64)".

Command(m for help):t
Partition number (1-3, default 3): 3
Partition type or alias (type L to list all): 23

Changed type of partition 'Linux filesystem' to 'Linux root (x86-64)'

Optionally, to have the root partition conform to the Discoverable System Partition (DSP) specification, switch to expert mode and perform the following extra step to set the partition's UUID:

Command (m for help):x
Expert command (m for help):u
Partition number (1-3, default 3): 3

New UUID (in 8-4-4-4-12 format): 4f68bce3-e8cd-4db1-96e7-fbcaf984b709

Partition UUID changed from 40465382-FA2A-4846-9827-640821CC001F to 4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709.

Press the r key to return to the main menu:

Expert command (m for help):r

Command (m for help):

After completing these steps, pressing p should display a partition table that looks similar to the following:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 3E56EE74-0571-462B-A992-9872E3855D75

Device        Start        End    Sectors   Size Type
/dev/sda1      2048    2099199    2097152     1G Linux filesystem
/dev/sda2   2099200   10487807    8388608     4G Linux swap
/dev/sda3  10487808 1953523711 1943035904 926.5G Linux root (x86-64)

Filesystem/RAID signature on partition 1 will be wiped.

Saving the partition layout

Press w to save the partition layout and exit the fdisk utility:

Command (m for help):w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

With partitions now available, the next installation step is to fill them with filesystems.

Partitioning the disk with MBR for BIOS / legacy boot

The following table provides a recommended partition layout for a trivial MBR DOS / legacy BIOS boot installation. Additional partitions can be added according to personal preference or system design goals.

Device path (sysfs) Mount point File system DPS UUID (PARTUUID) Description
/dev/sda1 /boot xfs N/A MBR DOS / legacy BIOS boot partition details.
/dev/sda2 N/A. Swap is not mounted to the filesystem like a device file. swap 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f Swap partition details.
/dev/sda3 / xfs 4f68bce3-e8cd-4db1-96e7-fbcaf984b709 Root partition details.

Change the partition layout according to personal preference.

Viewing the current partition layout

Fire up fdisk against the disk (in our example, we use /dev/sda):

root #fdisk /dev/sda

Use the p key to display the disk's current partition configuration:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xf163b576

Device     Boot    Start        End    Sectors   Size Id Type
/dev/sda1  *        2048    2099199    2097152     1G 83 Linux
/dev/sda2        2099200   10487807    8388608     4G 82 Linux swap / Solaris
/dev/sda3       10487808 1953525167 1943037360 926.5G 83 Linux

This particular disk was until now configured to house two Linux filesystems (each with a corresponding partition listed as "Linux") as well as a swap partition (listed as "Linux swap"), using a GPT table.

Creating a new disklabel / removing all partitions

Pressing o will instantly remove all existing disk partitions and create a new MBR disklabel (also named DOS disklabel):

Command (m for help):o
Created a new DOS disklabel with disk identifier 0xf163b576.
The device contains 'gpt' signature and it will be removed by a write command. See fdisk(8) man page and --wipe option for more details.

Alternatively, to keep an existing DOS disklabel (see the output of p above), consider removing the existing partitions one by one from the disk. Press d to delete a partition. For instance, to delete an existing /dev/sda1:

Command (m for help):d
Partition number (1-4): 1

The partition has now been scheduled for deletion. It will no longer show up when printing the list of partitions (p, but it will not be erased until the changes have been saved. This allows users to abort the operation if a mistake was made - in that case, type q immediately and hit Enter and the partition will not be deleted.

Repeatedly press p to print out a partition listing and then press d and the number of the partition to delete it. Eventually, the partition table will be empty:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xf163b576

The disk is now ready to create new partitions.

Creating the boot partition

First, create a small partition which will be mounted as /boot. Press n to create a new partition, followed by p for a primary partition and 1 to select the first primary partition. When prompted for the first sector, make sure it starts from 2048 (which may be needed for the boot loader) and press Enter. When prompted for the last sector, type +1G to create a partition 1 GB in size:

Command (m for help):n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-1953525167, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-1953525167, default 1953525167): +1G

Created a new partition 1 of type 'Linux' and of size 1 GiB.

Mark the partition as bootable by pressing the a key and pressing Enter:

Command (m for help):a
Selected partition 1
The bootable flag on partition 1 is enabled now.

Note: if more than one partition is available on the disk, then the partition to be flagged as bootable will have to be selected.

Creating the swap partition

Next, to create the swap partition, press n to create a new partition, then p, then type 2 to create the second primary partition, /dev/sda2. When prompted for the first sector, press Enter. When prompted for the last sector, type +4G (or any other size needed for the swap space) to create a partition 4GB in size.

Command (m for help):n
Partition type
   p   primary (1 primary, 0 extended, 3 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2): 2
First sector (2099200-1953525167, default 2099200):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2099200-1953525167, default 1953525167): +4G
 
Created a new partition 2 of type 'Linux' and of size 4 GiB.

After all this is done, press t to set the partition type, 2 to select the partition just created and then type in 82 to set the partition type to "Linux Swap".

Command (m for help):t
Partition number (1,2, default 2): 2
Hex code (type L to list all codes): 82

Changed type of partition 'Linux' to 'Linux swap / Solaris'.

Creating the root partition

Finally, to create the root partition, press n to create a new partition. Then press p and 3 to create the third primary partition, /dev/sda3. When prompted for the first sector, hit Enter. When prompted for the last sector, hit Enter to create a partition that takes up the rest of the remaining space on the disk:

Command (m for help):n
Partition type
   p   primary (2 primary, 0 extended, 2 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (3,4, default 3): 3
First sector (10487808-1953525167, default 10487808):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (10487808-1953525167, default 1953525167):

Created a new partition 3 of type 'Linux' and of size 926.5 GiB.

After completing these steps, pressing p should display a partition table that looks similar to this:

Command (m for help):p
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: HGST HTS721010A9
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xf163b576

Device     Boot    Start        End    Sectors   Size Id Type
/dev/sda1  *        2048    2099199    2097152     1G 83 Linux
/dev/sda2        2099200   10487807    8388608     4G 82 Linux swap / Solaris
/dev/sda3       10487808 1953525167 1943037360 926.5G 83 Linux

Saving the partition layout

Press w to write the partition layout and exit fdisk:

Command (m for help):w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Now it is time to put filesystems on the partitions.


Creating file systems

Warning
When using SSD or NVMe drive, it is wise to check for firmware upgrades. Some Intel SSDs in particular (600p and 6000p) require a firmware upgrade for possible data corruption induced by XFS I/O usage patterns. The problem is at the firmware level and not any fault of the XFS filesystem. The smartctl utility can help check the device model and firmware version.

Introduction

Now that the partitions have been created, it is time to place a filesystem on them. In the next section the various file systems that Linux supports are described. Readers that already know which filesystem to use can continue with Applying a filesystem to a partition. The others should read on to learn about the available filesystems...

Filesystems

Linux supports several dozen filesystems, although many of them are only wise to deploy for specific purposes. Only certain filesystems may be found stable on the amd64 architecture - it is advised to read up on the filesystems and their support state before selecting a more experimental one for important partitions. XFS is the recommended all-purpose, all-platform filesystem. The below is a non-exhaustive list:

btrfs
Newer generation filesystem. Provides advanced features like snapshotting, self-healing through checksums, transparent compression, subvolumes, and integrated RAID. Kernels prior to 5.4.y are not guaranteed to be safe to use with btrfs in production because fixes for serious issues are only present in the more recent releases of the LTS kernel branches. RAID 5/6 and quota groups unsafe on all versions of btrfs.
ext4
Ext4 is a reliable, all-purpose all-platform filesystem, although it lacks modern features like reflinks.
f2fs
The Flash-Friendly File System was originally created by Samsung for the use with NAND flash memory. It is a decent choice when installing Gentoo to microSD cards, USB drives, or other flash-based storage devices.
XFS
Filesystem with metadata journaling which comes with a robust feature-set and is optimized for scalability. It has been continuously upgraded to include modern features. The only downside is that XFS partitions cannot yet be shrunk, although this is being worked on. XFS notably supports reflinks and Copy on Write (CoW) which is particularly helpful on Gentoo systems because of the amount of compiles users complete. XFS is the recommended modern all-purpose all-platform filesystem. Requires a partition to be at least 300MB.
VFAT
Also known as FAT32, is supported by Linux but does not support standard UNIX permission settings. It is mostly used for interoperability/interchange with other operating systems (Microsoft Windows or Apple's macOS) but is also a necessity for some system bootloader firmware (like UEFI). Users of UEFI systems will need an EFI System Partition formatted with VFAT in order to boot.
NTFS
This "New Technology" filesystem is the flagship filesystem of Microsoft Windows since Windows NT 3.1. Similarly to VFAT, it does not store UNIX permission settings or extended attributes necessary for BSD or Linux to function properly, therefore it should not be used as a root filesystem for most cases. It should only be used for interoperability or data interchange with Microsoft Windows systems (note the emphasis on only).

More extensive information on filesystems can be found in the community maintained Filesystem article.

Applying a filesystem to a partition

Note
Please make sure to emerge the relevant user space utilities package for the chosen filesystem before rebooting. There will be a reminder to do so near the end of the installation process.

To create a filesystem on a partition or volume, there are user space utilities available for each possible filesystem. Click the filesystem's name in the table below for additional information on each filesystem:

Filesystem Creation command Within the live environment? Package
btrfs mkfs.btrfs Yes sys-fs/btrfs-progs
ext4 mkfs.ext4 Yes sys-fs/e2fsprogs
f2fs mkfs.f2fs Yes sys-fs/f2fs-tools
xfs mkfs.xfs Yes sys-fs/xfsprogs
vfat mkfs.vfat Yes sys-fs/dosfstools
NTFS mkfs.ntfs Yes sys-fs/ntfs3g
Important
The handbook recommends new partitions as part of the installation process, but it is important to note running any mkfs command will erase any data contained within the partition. When necessary, ensure any data that exists within is appropriately backed up before creating a few filesystem.

For instance, to have the root partition (/dev/sda3) as xfs as used in the example partition structure, the following commands would be used:

root #mkfs.xfs /dev/sda3

EFI system partition filesystem

The EFI system partition (/dev/sda1) must be formatted as FAT32:

root #mkfs.vfat -F 32 /dev/sda1

Legacy BIOS boot partition filesystem

Systems booting via legacy BIOS with a MBR/DOS disklabel can use any filesystem format supported by the bootloader.

For example, to format with XFS:

root #mkfs.xfs /dev/sda1

Small ext4 partitions

When using the ext4 filesystem on a small partition (less than 8 GiB), the filesystem should be created with the proper options to reserve enough inodes. This can specified using the -T small option:

root #mkfs.ext4 -T small /dev/<device>

Doing so will quadruple the number of inodes for a given filesystem, since its "bytes-per-inode" reduces from one every 16kB to one every 4kB.

Activating the swap partition

mkswap is the command that is used to initialize swap partitions:

root #mkswap /dev/sda2

To activate the swap partition, use swapon:

root #swapon /dev/sda2

This 'activation' step is only necessary because the swap partition is newly created within the live environment. Once the system has been rebooted, as long as the swap partition is properly defined within fstab or other mount mechanism, swap space will activate automatically.

Mounting the root partition

Note
Installations which were previously started, but did not finish the installation process can resume the installation from this point in the handbook. Use this link as the permalink: Resumed installations start here.

Certain live environments may be missing the suggested mount point for Gentoo's root partition (/mnt/gentoo), or mount points for additional partitions created in the partitioning section:

root #mkdir --parents /mnt/gentoo

For EFI installs only, the ESP should be mounted under the root partition location:

root #mkdir --parents /mnt/gentoo/efi

Continue creating additional mount points necessary for any additional (custom) partition(s) created during previous steps by using the mkdir command.

With mount points created, it is time to make the partitions accessible via mount command.

Mount the root partition:

root #mount /dev/sda3 /mnt/gentoo

Continue mounting additional (custom) partitions as necessary using the mount command.

Note
If /tmp/ needs to reside on a separate partition, be sure to change its permissions after mounting:
root #chmod 1777 /mnt/gentoo/tmp
This also holds for /var/tmp.

Later in the instructions, the proc filesystem (a virtual interface with the kernel) as well as other kernel pseudo-filesystems will be mounted. But first the Gentoo stage file must be extracted.





Choosing a stage file

Tip
On supported architectures, it is recommended for users targeting a desktop (graphical) operating system environment to use a stage file with the term desktop within the name. These files include packages such as sys-devel/llvm and dev-lang/rust-bin and USE flag tuning which will greatly improve install time.

The stage file acts as the seed of a Gentoo install. Stage files are generated with Catalyst by the Release Engineering Team. Stage files are based on specific profiles, and contain an almost-complete system.

When choosing a stage file, it's important to pick one with profile targets corresponding to the desired system type.

Important
While it's possible to make major profile changes after an installation has been established, switching requires substantial effort and consideration, and is outside the scope of this installation manual. Switching init systems is difficult, but switching from no-multilib to multilib requires extensive Gentoo and low-level toolchain knowledge.
Tip
Most users should not need to use the 'advanced' tarballs options; they are for atypical or advanced software or hardware configurations.

OpenRC

OpenRC is a dependency-based init system (responsible for starting up system services once the kernel has booted) that maintains compatibility with the system provided init program, normally located in /sbin/init. It is Gentoo's native and original init system, but is also deployed by a few other Linux distributions and BSD systems.

OpenRC does not function as a replacement for the /sbin/init file by default and is 100% compatible with Gentoo init scripts. This means a solution can be found to run the dozens of daemons in the Gentoo ebuild repository.

systemd

systemd is a modern SysV-style init and rc replacement for Linux systems. It is used as the primary init system by a majority of Linux distributions. systemd is fully supported in Gentoo and works for its intended purpose. If something seems lacking in the Handbook for a systemd install path, review the systemd article before asking for support.

Multilib (32 and 64-bit)

Note
Not every architecture has a multilib option. Many only run with native code. Multilib is most commonly applied to amd64.

The multilib profile uses 64-bit libraries when possible, and only falls back to the 32-bit versions when strictly necessary for compatibility. This is an excellent option for the majority of installations because it provides a great amount of flexibility for customization in the future.

Tip
Using multilib targets makes it easier to switch profiles later, compared to no-multilib

No-multilib (pure 64-bit)

Warning
Readers who are just starting out with Gentoo should not choose a no-multilib tarball unless it is absolutely necessary. Migrating from a no-multilib to a multilib system requires an extremely well-working knowledge of Gentoo and the lower-level toolchain (it may even cause our Toolchain developers to shudder a little). It is not for the faint of heart and is beyond the scope of this guide.

Selecting a no-multilib tarball to be the base of the system provides a complete 64-bit operating system environment - free of 32-bit software. This effectively renders the ability to switch to multilib profiles burdensome, although still technically possible.

Downloading the stage file

Before downloading the stage file, the current directory should be set to the location of the mount used for the install:

root #cd /mnt/gentoo

Setting the date and time

Stage archives are generally obtained using HTTPS which requires relatively accurate system time. Clock skew can prevent downloads from working, and can cause unpredictable errors if the system time is adjusted by any considerable amount after installation.

The current date and time can be verified with date:

root #date
Mon Oct  3 13:16:22 PDT 2021

If the displayed date/time is more than few minutes off, it should be updated using one of the following methods.

Automatic

Using NTP to correct clock skew is typically easier and more reliable than manually setting the system clock.

chronyd, part of net-misc/chrony can be used to update the system clock to UTC with:

root #chronyd -q
Important
Systems without a functioning Real-Time Clock (RTC) must sync the system clock at every system start, and on regular intervals thereafter. This is also beneficial for systems with a RTC, as the battery could fail, and clock skew can accumulate.
Warning
Standard NTP traffic not authenticated, it is important to verify time data obtained from the network.

Manual

When NTP access is unavailable, date can be used to manually set the system clock.

Note
UTC time is recommended for all Linux systems. Later, a system timezone is defined, which changes the offset when the date is displayed.

The following argument format is used to set the time: MMDDhhmmYYYY syntax (Month, Day, hour, minute and Year).

For instance, to set the date to October 3rd, 13:16 in the year 2021, issue:

root #date 100313162021

Graphical browsers

Those using environments with fully graphical web browsers will have no problem copying a stage file URL from the main website's download section. Simply select the appropriate tab, right click the link to the stage file, then Copy Link to copy the link to the clipboard, then paste the link to the wget utility on the command-line to download the stage file:

root #wget <PASTED_STAGE_FILE_URL>

Command-line browsers

More traditional readers or 'old timer' Gentoo users, working exclusively from command-line may prefer using links (www-client/links), a non-graphical, menu-driven browser. To download a stage, surf to the Gentoo mirror list like so:

root #links https://www.gentoo.org/downloads/mirrors/

To use an HTTP proxy with links, pass on the URL with the -http-proxy option:

root #links -http-proxy proxy.server.com:8080 https://www.gentoo.org/downloads/mirrors/

Next to links there is also the lynx (www-client/lynx) browser. Like links it is a non-graphical browser but it is not menu-driven.

root #lynx https://www.gentoo.org/downloads/mirrors/

If a proxy needs to be defined, export the http_proxy and/or ftp_proxy variables:

root #export http_proxy="http://proxy.server.com:port"
root #export ftp_proxy="http://proxy.server.com:port"

On the mirror list, select a mirror close by. Usually HTTP mirrors suffice, but other protocols are available as well. Move to the releases/amd64/autobuilds/ directory. There all available stage files are displayed (they might be stored within subdirectories named after the individual sub-architectures). Select one and press d to download.

After the stage file download completes, it is possible to verify the integrity and validate the contents of the stage file. Those interested should proceed to the next section.

Those not interested in verifying and validating the stage file can close the command-line browser by pressing q and can move directly to the Unpacking the stage file section.

Verifying and validating

Note
Most stages are now explicitly suffixed with the init system type (openrc or systemd), although some architectures may still be missing these for now.

Like with the minimal installation CDs, additional downloads to verify and validate the stage file are available. Although these steps may be skipped, these files are provided for users who care about the integrity of the file(s) they just downloaded. The extra files are available under the root of the mirrors directory. Browse to the appropriate location for the hardware architecture and the system profile and download the associated .CONTENTS.gz, .DIGESTS, and .sha256 files.

root #wget https://distfiles.gentoo.org/releases/
  • .CONTENTS.gz - A compressed file that contains a list of all files inside the stage file.
  • .DIGESTS - Contains checksums of the stage file in using several cryptographic hash algorithms.
  • .sha256 - Contains a PGP signed SHA256 checksum of the stage file. This file may not be available for download for all stage files.

Cryptographic tools and utilities such as openssl, sha256sum, or sha512sum can be used to compare the output with the checksums provided by the .DIGESTS file.

To verify the SHA512 checksum with openssl:

root #openssl dgst -r -sha512 stage3-amd64-<release>-<init>.tar.xz

dgst instructs the openssl command to use the Message Digest sub-command, -r prints the digest output in coreutils format, and -sha512 selects the SHA512 digest.

To verify the BLAKE2B512 checksum with openssl:

root #openssl dgst -r -blake2b512 stage3-amd64-<release>-<init>.tar.xz

Compare the output(s) of the checksum commands with the hash and filename paired values contained within the .DIGESTS file. The paired values need to match the output of the checksum commands, otherwise the downloaded file is corrupt can should be discarded and re-downloaded.

To verify the SHA256 hash from an associated .sha256 file using the sha256sum utility:

root #sha256sum --check stage3-amd64-<release>-<init>.tar.xz.sha256

The --check option instructs sha256sum to read a list of expected files and associated hashes, and then print an associated "OK" for each file that calculates correctly or a "FAILED" for files that do not.

Just like with the ISO file, the cryptographic signature of the tar.xz file can be verified using gpg to ensure no tampering has been performed on the tarball.

For official Gentoo live images, the sec-keys/openpgp-keys-gentoo-release package provides PGP signing keys for automated releases. The keys must first be imported into the user's session in order to be used for verification:

root #gpg --import /usr/share/openpgp-keys/gentoo-release.asc

For all non-official live images which offer gpg and wget in the live environment, a bundle containing Gentoo keys can be fetched and imported:

root #wget -O - https://qa-reports.gentoo.org/output/service-keys.gpg | gpg --import

Verify the signature of the tarball and, optionally, associated checksum files:

root #gpg --verify stage3-amd64-<release>-<init>.tar.xz.asc
root #gpg --verify stage3-amd64-<release>-<init>.tar.xz.DIGESTS
root #gpg --verify stage3-amd64-<release>-<init>.tar.xz.sha256

If verification succeeds, "Good signature from" will be in the output of the previous command(s).

The fingerprints of the OpenPGP keys used for signing release media can be found on the release media signatures page.

Installing a stage file

Once the stage file has been downloaded and verified, it can be extracted using tar:

root #tar xpvf stage3-*.tar.xz --xattrs-include='*.*' --numeric-owner

Before extracting verify the options:

  • x extract, instructs tar to extract the contents of the archive.
  • p preserve permissions.
  • v verbose output.
  • f file, provides tar with the name of the input archive.
  • --xattrs-include='*.*' Preserves extended attributes in all namespaces stored in the archive.
  • --numeric-owner Ensure that the user and group IDs of files being extracted from the tarball remain the same as Gentoo's release engineering team intended (even if adventurous users are not using official Gentoo live environments for the installation process).

Now that the stage file is unpacked, proceed with Configuring compile options.

Configuring compile options

Introduction

To optimize the system, it is possible to set variables which impact the behavior of Portage, Gentoo's officially supported package manager. All those variables can be set as environment variables (using export) but setting via export is not permanent.

Note
Technically variables can be exported via the shell's profile or rc files, however that is not best practice for basic system administration.

Portage reads in the make.conf file when it runs, which will change runtime behavior depending on the values saved in the file. make.conf can be considered the primary configuration file for Portage, so treat its content carefully.

Tip
A commented listing of all possible variables can be found in /mnt/gentoo/usr/share/portage/config/make.conf.example. Additional documentation on make.conf can be found by running man 5 make.conf.

For a successful Gentoo installation only the variables that are mentioned below need to be set.

Fire up an editor (in this guide we use nano) to alter the optimization variables we will discuss hereafter.

root #nano /mnt/gentoo/etc/portage/make.conf

From the make.conf.example file it is obvious how the file should be structured: commented lines start with #, other lines define variables using the VARIABLE="value" syntax. Several of those variables are discussed in the next section.

CFLAGS and CXXFLAGS

The CFLAGS and CXXFLAGS variables define the optimization flags for GCC C and C++ compilers respectively. Although those are defined generally here, for maximum performance one would need to optimize these flags for each program separately. The reason for this is because every program is different. However, this is not manageable, hence the definition of these flags in the make.conf file.

In make.conf one should define the optimization flags that will make the system the most responsive generally. Don't place experimental settings in this variable; too much optimization can make programs misbehave (crash, or even worse, malfunction).

The Handbook will not explain all possible optimization options. To understand them all, read the GNU Online Manual(s) or the gcc info page (info gcc). The make.conf.example file itself also contains lots of examples and information; don't forget to read it too.

A first setting is the -march= or -mtune= flag, which specifies the name of the target architecture. Possible options are described in the make.conf.example file (as comments). A commonly used value is native as that tells the compiler to select the target architecture of the current system (the one users are installing Gentoo on).

A second one is the -O flag (that is a capital O, not a zero), which specifies the gcc optimization class flag. Possible classes are s (for size-optimized), 0 (zero - for no optimizations), 1, 2 or even 3 for more speed-optimization flags (every class has the same flags as the one before, plus some extras). -O2 is the recommended default. -O3 is known to cause problems when used system-wide, so we recommend to stick to -O2.

Another popular optimization flag is -pipe (use pipes rather than temporary files for communication between the various stages of compilation). It has no impact on the generated code, but uses more memory. On systems with low memory, gcc might get killed. In that case, do not use this flag.

Using -fomit-frame-pointer (which doesn't keep the frame pointer in a register for functions that don't need one) might have serious repercussions on the debugging of applications.

When the CFLAGS and CXXFLAGS variables are defined, combine the several optimization flags in one string. The default values contained in the stage file archive should be good enough. The following one is just an example:

CODE Example CFLAGS and CXXFLAGS variables
# Compiler flags to set for all languages
COMMON_FLAGS="-march=native -O2 -pipe"
# Use the same settings for both variables
CFLAGS="${COMMON_FLAGS}"
CXXFLAGS="${COMMON_FLAGS}"
Tip
Although the GCC optimization article has more information on how the various compilation options can affect a system, the Safe CFLAGS article may be a more practical place for beginners to start optimizing their systems.

MAKEOPTS

The MAKEOPTS variable defines how many parallel compilations should occur when installing a package. As of Portage version 3.0.31[1], if left undefined, Portage's default behavior is to set the MAKEOPTS jobs value to the same number of threads returned by nproc.

Further, as of Portage 3.0.53[2], if left undefined, Portage's default behavior is to set the MAKEOPTS load-average value to the same number of threads returned by nproc.

A good choice is the smaller of: the number of threads the CPU has, or the total amount of system RAM divided by 2 GiB.

Warning
Using a large number of jobs can significantly impact memory consumption. A good recommendation is to have at least 2 GiB of RAM for every job specified (so, e.g. -j6 requires at least 12 GiB). To avoid running out of memory, lower the number of jobs to fit the available memory.
Tip
When using parallel emerges (--jobs), the effective number of jobs run can grow exponentially (up to make jobs multiplied by emerge jobs). This can be worked around by running a localhost-only distcc configuration that will limit the number of compiler instances per host.
FILE /etc/portage/make.confExample MAKEOPTS declaration
# If left undefined, Portage's default behavior is to:
# - set the MAKEOPTS jobs value to the same number of threads returned by `nproc`
# - set the MAKEOPTS load-average value slightly above the number of threads returned by `nproc`, due to it being a damped value
# Please replace '4' as appropriate for the system (min(RAM/2GB, threads), or leave it unset.
MAKEOPTS="-j4 -l5"

Search for MAKEOPTS in man 5 make.conf for more details.

Ready, set, go!

Update the /mnt/gentoo/etc/portage/make.conf file to match personal preference and save (nano users would press Ctrl+o to write the change and then Ctrl+x to quit).

References





Chrooting

Copy DNS info

One thing still remains to be done before entering the new environment and that is copying over the DNS information in /etc/resolv.conf. This needs to be done to ensure that networking still works even after entering the new environment. /etc/resolv.conf contains the name servers for the network.

To copy this information, it is recommended to pass the --dereference option to the cp command. This ensures that, if /etc/resolv.conf is a symbolic link, that the link's target file is copied instead of the symbolic link itself. Otherwise in the new environment the symbolic link would point to a non-existing file (as the link's target is most likely not available inside the new environment).

root #cp --dereference /etc/resolv.conf /mnt/gentoo/etc/

Mounting the necessary filesystems

In a few moments, the Linux root will be changed towards the new location.

The filesystems that need to be made available are:

  • /proc/ is a pseudo-filesystem. It looks like regular files, but is generated on-the-fly by the Linux kernel
  • /sys/ is a pseudo-filesystem, like /proc/ which it was once meant to replace, and is more structured than /proc/
  • /dev/ is a regular file system which contains all device. It is partially managed by the Linux device manager (usually udev)
  • /run/ is a temporary file system used for files generated at runtime, such as PID files or locks

The /proc/ location will be mounted on /mnt/gentoo/proc/ whereas the others are bind-mounted. The latter means that, for instance, /mnt/gentoo/sys/ will actually be /sys/ (it is just a second entry point to the same filesystem) whereas /mnt/gentoo/proc/ is a new mount (instance so to speak) of the filesystem.

Tip
If using Gentoo's install media, this step can be replaced with simply: arch-chroot /mnt/gentoo.
root #mount --types proc /proc /mnt/gentoo/proc
root #mount --rbind /sys /mnt/gentoo/sys
root #mount --make-rslave /mnt/gentoo/sys
root #mount --rbind /dev /mnt/gentoo/dev
root #mount --make-rslave /mnt/gentoo/dev
root #mount --bind /run /mnt/gentoo/run
root #mount --make-slave /mnt/gentoo/run
Note
The --make-rslave operations are needed for systemd support later in the installation.
Warning
When using non-Gentoo installation media, this might not be sufficient. Some distributions make /dev/shm a symbolic link to /run/shm/ which, after the chroot, becomes invalid. Making /dev/shm/ a proper tmpfs mount up front can fix this:
root #test -L /dev/shm && rm /dev/shm && mkdir /dev/shm
root #mount --types tmpfs --options nosuid,nodev,noexec shm /dev/shm

Also ensure that mode 1777 is set:

root #chmod 1777 /dev/shm /run/shm

Entering the new environment

Now that all partitions are initialized and the base environment installed, it is time to enter the new installation environment by chrooting into it. This means that the session will change its root (most top-level location that can be accessed) from the current installation environment (installation CD or other installation medium) to the installation system (namely the initialized partitions). Hence the name, change root or chroot.

This chrooting is done in three steps:

  1. The root location is changed from / (on the installation medium) to /mnt/gentoo/ (on the partitions) using chroot or arch-chroot, if available.
  2. Some settings (those in /etc/profile) are reloaded in memory using the source command
  3. The primary prompt is changed to help us remember that this session is inside a chroot environment.
root #chroot /mnt/gentoo /bin/bash
root #source /etc/profile
root #export PS1="(chroot) ${PS1}"

From this point, all actions performed are immediately on the new Gentoo Linux environment.

Tip
If the Gentoo installation is interrupted anywhere after this point, it should be possible to 'resume' the installation at this step. There is no need to re-partition the disks again! Simply mount the root partition and run the steps above starting with copying the DNS info to re-enter the working environment. This is also useful for fixing bootloader issues. More information can be found in the chroot article.

Preparing for a bootloader

Now that the new environment has been entered, it is necessary to prepare the new environment for the bootloader. It will be important to have the correct partition mounted when it is time to install the bootloader.

UEFI systems

For UEFI systems, /dev/sda1 was formatted with the FAT32 filesystem and will be used as the EFI System Partition (ESP). Create a new /efi directory (if not yet created), and then mount ESP there:

root #mkdir /efi
root #mount /dev/sda1 /efi

DOS/Legacy BIOS systems

For DOS/Legacy BIOS systems, the bootloader will be installed into the /boot directory, therefore mount as follows:

root #mount /dev/sda1 /boot

Configuring Portage

Installing a Gentoo ebuild repository snapshot from the web

Next step is to install a snapshot of the Gentoo ebuild repository. This snapshot contains a collection of files that informs Portage about available software titles (for installation), which profiles the system administrator can select, package or profile specific news items, etc.

The use of emerge-webrsync is recommended for those who are behind restrictive firewalls (it uses HTTP/FTP protocols for downloading the snapshot) and saves network bandwidth. Readers who have no network or bandwidth restrictions can happily skip down to the next section.

This will fetch the latest snapshot (which is released on a daily basis) from one of Gentoo's mirrors and install it onto the system:

root #emerge-webrsync
Note
During this operation, emerge-webrsync might complain about a missing /var/db/repos/gentoo/ location. This is to be expected and nothing to worry about - the tool will create the location.

From this point onward, Portage might mention that certain updates are recommended to be executed. This is because system packages installed through the stage file might have newer versions available; Portage is now aware of new packages because of the repository snapshot. Package updates can be safely ignored for now; updates can be delayed until after the Gentoo installation has finished.


Optional: Selecting mirrors

In order to download source code quickly it is recommended to select a fast, geographically close mirror. Portage will look in the make.conf file for the GENTOO_MIRRORS variable and use the mirrors listed therein. It is possible to surf to the Gentoo mirror list and search for a mirror (or multiple mirrors) close to the system's physical location (as those are most frequently the fastest ones).

A tool called mirrorselect provides a pretty text interface to more quickly query and select suitable mirrors. Just navigate to the mirrors of choice and press Spacebar to select one or more mirrors.

root #emerge --ask --verbose --oneshot app-portage/mirrorselect
root #mirrorselect -i -o >> /etc/portage/make.conf

Alternatively, a list of active mirrors are available online.

Optional: Updating the Gentoo ebuild repository

It is possible to update the Gentoo ebuild repository to the latest version. The previous emerge-webrsync command will have installed a very recent snapshot (usually recent up to 24h) so this step is definitely optional.

Suppose there is a need for the latest package updates (up to 1 hour), then use emerge --sync. This command will use the rsync protocol to update the Gentoo ebuild repository (which was fetched earlier on through emerge-webrsync) to the latest state.

root #emerge --sync

On slow terminals, such as certain frame buffers or serial consoles, it is recommended to use the --quiet option to speed up the process:

root #emerge --sync --quiet

Reading news items

When the Gentoo ebuild repository is synchronized, Portage may output informational messages similar to the following:

* IMPORTANT: 2 news items need reading for repository 'gentoo'.
* Use eselect news to read news items.

News items were created to provide a communication medium to push critical messages to users via the Gentoo ebuild repository. To manage them, use eselect news. The eselect application is a Gentoo-specific utility that allows for a common management interface for system administration. In this case, eselect is asked to use its news module.

For the news module, three operations are most used:

  • With list an overview of the available news items is displayed.
  • With read the news items can be read.
  • With purge news items can be removed once they have been read and will not be reread anymore.
root #eselect news list
root #eselect news read

More information about the news reader is available through its manual page:

root #man news.eselect

Choosing the right profile

Tip
Desktop profiles are not exclusively for desktop environments. They are also suitable for minimal window managers like i3 or sway.

A profile is a building block for any Gentoo system. Not only does it specify default values for USE, CFLAGS, and other important variables, it also locks the system to a certain range of package versions. These settings are all maintained by Gentoo's Portage developers.

To see what profile the system is currently using, run eselect using the profile module:

root #eselect profile list
Available profile symlink targets:
  [1]   default/linux/amd64/23.0 *
  [2]   default/linux/amd64/23.0/desktop
  [3]   default/linux/amd64/23.0/desktop/gnome
  [4]   default/linux/amd64/23.0/desktop/kde
Note
The output of the command is just an example and evolves over time.
Note
To use systemd, select a profile which has "systemd" in the name and vice versa, if not

There are also desktop sub-profiles available for some architectures which include software packages commonly necessary for a desktop experience.

Warning
Profile upgrades are not to be taken lightly. When selecting the initial profile, use the profile corresponding to the same version as the one initially used by the stage file (e.g. 23.0). Each new profile version is announced through a news item containing migration instructions; be sure to carefully follow the instructions before switching to a newer profile.

After viewing the available profiles for the amd64 architecture, users can select a different profile for the system:

root #eselect profile set 2


No-multilib

In order to select a pure 64-bit environment, with no 32-bit applications or libraries, use a no-multilib profile:

root #eselect profile list
Available profile symlink targets:
  [1]   default/linux/amd64/23.0 *
  [2]   default/linux/amd64/23.0/desktop
  [3]   default/linux/amd64/23.0/desktop/gnome
  [4]   default/linux/amd64/23.0/desktop/kde
  [5]   default/linux/amd64/23.0/no-multilib

Next select the no-multilib profile:

root #eselect profile set 5
root #eselect profile list
Available profile symlink targets:
  [1]   default/linux/amd64/23.0
  [2]   default/linux/amd64/23.0/desktop
  [3]   default/linux/amd64/23.0/desktop/gnome
  [4]   default/linux/amd64/23.0/desktop/kde
  [5]   default/linux/amd64/23.0/no-multilib *



Note
The developer sub-profile is specifically for Gentoo Linux development and is not meant to be used by casual users.

Optional: Adding a binary package host

Since December 2023, Gentoo's Release Engineering team has offered an official binary package host (colloquially shorted to just "binhost") for use by the general community to retrieve and install binary packages (binpkgs).[1]

Adding a binary package host allows Portage to install cryptographically signed, compiled packages. In many cases, adding a binary package host will greatly decrease the mean time to package installation and adds much benefit when running Gentoo on older, slower, or low power systems.

Repository configuration

The repository configuration for a binhost is found in Portage's /etc/portage/binrepos.conf/ directory, which functions similarly to the configuration mentioned in the Gentoo ebuild repository section.

When defining a binary host, there are two important aspects to consider:

  1. The architecture and profile targets within the sync-uri value do matter and should align to the respective computer architecture (amd64 in this case) and system profile selected in the Choosing the right profile section.
  2. Selecting a fast, geographically close mirror will generally shorten retrieval time. Review the mirrorselect tool mentioned in the Optional: Selecting mirrors section or review the online list of mirrors where URL values can be discovered.

FILE /etc/portage/binrepos.conf/gentoobinhost.confCDN-based binary package host example
[binhost]
priority = 9999
sync-uri = https://distfiles.gentoo.org/releases/<arch>/binpackages/<profile>/x86-64/

Installing binary packages

Portage will compile packages from code source by default. It can be instructed to use binary packages in the following ways:

  1. The --getbinpkg option can be passed when invoking the emerge command. This method of for binary package installation is useful to install only a particular binary package.
  2. Changing the system's default via Portage's FEATURES variable, which is exposed through the /etc/portage/make.conf file. Applying this configuration change will cause Portage to query the binary package host for the package(s) to be requested and fall back to compiling locally when no results are found.

For example, to have Portage always install available binary packages:

FILE /etc/portage/make.confConfigure Portage to use binary packages by default
# Appending getbinpkg to the list of values within the FEATURES variable
FEATURES="${FEATURES} getbinpkg"
# Require signatures
FEATURES="${FEATURES} binpkg-request-signature"

Please also run getuto for Portage to set up the necessary keyring for verification:

root #getuto

Additional Portage features will be discussed in the the next chapter of the handbook.

Optional: Configuring the USE variable

USE is one of the most powerful variables Gentoo provides to its users. Several programs can be compiled with or without optional support for certain items. For instance, some programs can be compiled with support for GTK+ or with support for Qt. Others can be compiled with or without SSL support. Some programs can even be compiled with framebuffer support (svgalib) instead of X11 support (X-server).

Most distributions compile their packages with support for as much as possible, increasing the size of the programs and startup time, not to mention an enormous amount of dependencies. With Gentoo, users can define what options for which a package should be compiled. This is where USE comes into play.

In the USE variable users define keywords which are mapped onto compile-options. For instance, ssl will compile SSL support in the programs that support it. -X will remove X-server support (note the minus sign in front). gnome gtk -kde -qt5 will compile programs with GNOME (and GTK+) support, and not with KDE (and Qt) support, making the system fully tweaked for GNOME (if the architecture supports it).

The default USE settings are placed in the make.defaults files of the Gentoo profile used by the system. Gentoo uses a complex inheritance system for system profiles, which will not be covered in depth during the installation process. The easiest way to check the currently active USE settings is to run emerge --info and select the line that starts with USE:

root #emerge --info | grep ^USE
USE="X acl alsa amd64 berkdb bindist bzip2 cli cracklib crypt cxx dri ..."
Note
The above example is truncated, the actual list of USE values is much, much larger.

A full description on the available USE flags can be found on the system in /var/db/repos/gentoo/profiles/use.desc.

root #less /var/db/repos/gentoo/profiles/use.desc

Inside the less command, scrolling can be done using the and keys, and exited by pressing q.

As an example we show a USE setting for a KDE-based system with DVD, ALSA, and CD recording support:

root #nano /etc/portage/make.conf
FILE /etc/portage/make.confEnabling flags for a KDE/Plasma-based system with DVD, ALSA, and CD recording support
USE="-gtk -gnome qt5 kde dvd alsa cdr"

When a USE value is defined in /etc/portage/make.conf it is added to the system's USE flag list. USE flags can be globally removed by adding a - minus sign in front of the value in the the list. For example, to disable support for X graphical environments, -X can be set:

FILE /etc/portage/make.confIgnoring default USE flags
USE="-X acl alsa"
Warning
Although possible, setting -* (which will disable all USE values except the ones specified in make.conf) is strongly discouraged and unwise. Ebuild developers choose certain default USE flag values in ebuilds in order to prevent conflicts, enhance security, and avoid errors, and other reasons. Disabling all USE flags will negate default behavior and may cause major issues.

CPU_FLAGS_*

Some architectures (including AMD64/X86, ARM, PPC) have a USE_EXPAND variable called CPU_FLAGS_<ARCH>, where <ARCH> is replaced with the relevant system architecture name.

Important
Do not be confused! AMD64 and X86 systems share some common architecture, so the proper variable name for AMD64 systems is CPU_FLAGS_X86.

This is used to configure the build to compile in specific assembly code or other intrinsics, usually hand-written or otherwise extra, and is not the same as asking the compiler to output optimized code for a certain CPU feature (e.g. -march=).

Users should set this variable in addition to configuring their COMMON_FLAGS as desired.

A few steps are needed to set this up:

root #emerge --ask --oneshot app-portage/cpuid2cpuflags

Inspect the output manually if curious:

root #cpuid2cpuflags

Then copy the output into package.use:

root #echo "*/* $(cpuid2cpuflags)" > /etc/portage/package.use/00cpu-flags

VIDEO_CARDS

The VIDEO_CARDS USE_EXPAND variable should be configured appropriately depending on the available GPU(s). Setting VIDEO_CARDS is not required for a console only install.

Below is an example of a properly set VIDEO_CARDS variable. Substitute the name of the driver(s) to be used.

FILE /etc/portage/make.conf
VIDEO_CARDS="amdgpu radeonsi"

Details for various GPU(s) can be found at the AMDGPU, Intel, Nouveau (Open Source), or NVIDIA (Proprietary) articles.

Optional: Configure the ACCEPT_LICENSE variable

Starting with Gentoo Linux Enhancement Proposal 23 (GLEP 23), a mechanism was created to allow system administrators the ability to "regulate the software they install with regards to licenses... Some want a system free of any software that is not OSI-approved; others are simply curious as to what licenses they are implicitly accepting."[2] With a motivation to have more granular control over the type of software running on a Gentoo system, the ACCEPT_LICENSE variable was born.

During the installation process, Portage considers the value(s) set within the ACCEPT_LICENSE variable to determine if the requested package(s) meet the sysadmin's determination of an acceptable license. Here in lies a problem: the Gentoo ebuild repository is filled with thousands of ebuilds which results in hundreds of distinct software licenses... Does this implicate sysadmin into individually approving each and every new software license? Thankfully no; GLEP 23 also outlines a solution to this problem, a concept called license groups.

For the convenience of system administration, legally-similar software licenses have been bundled together - each according to its like-kind. License group definitions are available for viewing and are managed by the Gentoo Licenses project. While an individual license is not, license groups are syntactically preceded with an @ symbol, enabling them to be easily distinguished in the ACCEPT_LICENSE variable.

Some common license groups include:

A list of software licenses grouped according to their kinds.
Name Description
@GPL-COMPATIBLE GPL compatible licenses approved by the Free Software Foundation [a_license 1]
@FSF-APPROVED Free software licenses approved by the FSF (includes @GPL-COMPATIBLE)
@OSI-APPROVED Licenses approved by the Open Source Initiative [a_license 2]
@MISC-FREE Misc licenses that are probably free software, i.e. follow the Free Software Definition [a_license 3] but are not approved by either FSF or OSI
@FREE-SOFTWARE Combines @FSF-APPROVED, @OSI-APPROVED, and @MISC-FREE.
@FSF-APPROVED-OTHER FSF-approved licenses for "free documentation" and "works of practical use besides software and documentation" (including fonts)
@MISC-FREE-DOCS Misc licenses for free documents and other works (including fonts) that follow the free definition [a_license 4] but are NOT listed in @FSF-APPROVED-OTHER.
@FREE-DOCUMENTS Combines @FSF-APPROVED-OTHER and @MISC-FREE-DOCS.
@FREE Metaset of all licenses with the freedom to use, share, modify and share modifications. Combines @FREE-SOFTWARE and @FREE-DOCUMENTS.
@BINARY-REDISTRIBUTABLE Licenses that at least permit free redistribution of the software in binary form. Includes @FREE.
@EULA License agreements that try to take away your rights. These are more restrictive than "all-rights-reserved" or require explicit approval

Currently set system wide acceptable license values can be viewed via:

user $portageq envvar ACCEPT_LICENSE
@FREE

As visible in the output, the default value is to only allow software which has been grouped into the @FREE category to be installed.

Specific licenses or licenses groups for a system can be defined in the following locations:

  • System wide within the selected profile - this sets the default value.
  • System wide within the /etc/portage/make.conf file. System administrators override the profile's default value within this file.
  • Per-package within a /etc/portage/package.license file.
  • Per-package within a /etc/portage/package.license/ directory of files.

The system wide license default in the profile is overridden within the /etc/portage/make.conf:

FILE /etc/portage/make.confAccept licenses with ACCEPT_LICENSE system wide
# Overrides the profile's ACCEPT_LICENSE default value
ACCEPT_LICENSE="-* @FREE @BINARY-REDISTRIBUTABLE"

Optionally system administrators can also define accepted licenses per-package as shown in the following directory of files example. Note that the package.license directory will need created if it does not already exist:

root #mkdir /etc/portage/package.license

Software license details for an individual Gentoo package are stored within the LICENSE variable of the associated ebuild. One package may have one or many software licenses, therefore it be necessary to specify multiple acceptable licenses for a single package.

FILE /etc/portage/package.license/kernelAccepting licenses on a per-package basis
app-arch/unrar unRAR
sys-kernel/linux-firmware @BINARY-REDISTRIBUTABLE
sys-firmware/intel-microcode intel-ucode
Important
The LICENSE variable in an ebuild is only a guideline for Gentoo developers and users. It is not a legal statement, and there is no guarantee that it will reflect reality. It is recommended to not solely rely on a ebuild developer's interpretation of a software package's license; but check the package itself in depth, including all files that have been installed to the system.

Optional: Updating the @world set

Updating the system's @world set is optional and will be unlikely to perform functional changes unless one or more of the following optional steps have been performed:

  1. A profile target different from the stage file has been selected.
  2. Additional USE flags have been set for installed packages.

Readers who are performing an 'install Gentoo speed run' may safely skip @world set updates until after their system has rebooted into the new Gentoo environment.

Readers who are performing a slow run can have Portage perform updates for package, profile, and/or USE flag changes at the present time:

root #emerge --ask --verbose --update --deep --newuse @world

Removing obsolete packages

It is important to always depclean after system upgrades to remove obsolete packages. Review the output carefully with emerge --depclean --pretend to see if any of the to-be-cleaned packages should be kept if personally using them. To keep a package which would otherwise be depcleaned, use emerge --noreplace foo.

root #emerge --ask --pretend --depclean

If happy, then proceed with a real depclean:

root #emerge --ask --depclean
Tip
If a desktop environment profile target has been selected from a non-desktop stage file, the @world update process could greatly extend the amount of time necessary for the install process. Those in a time crunch can work by this 'rule of thumb': the shorter the profile name, the less specific the system's @world set. The less specific the @world set, the fewer packages the system will require. E.g.:
  • Selecting default/linux/amd64/23.0 will likely require fewer packages to be updated, whereas
  • Selecting default/linux/amd64/23.0/desktop/gnome/systemd will likely require more packages to be installed since the profile target has a larger @system and @profile sets: dependencies supporting the GNOME desktop environment.

Optional: Using systemd as the system and service manager

The remainder of the Gentoo handbook will provide systemd steps alongside OpenRC (the traditional Gentoo init system) where separate steps or recommendations are necessary. System administrators should also consult the systemd article for more details on managing systemd as the system and service manager.

Timezone

Note
This step does not apply to users of the musl libc. Users who do not know what that means should perform this step.
Warning
Please avoid the /usr/share/zoneinfo/Etc/GMT* timezones as their names do not indicate the expected zones. For instance, GMT-8 is in fact GMT+8.

Select the timezone for the system. Look for the available timezones in /usr/share/zoneinfo/:

root #ls -l /usr/share/zoneinfo
total 352
drwxr-xr-x 2 root root   1120 Jan  7 17:41 Africa
drwxr-xr-x 6 root root   2960 Jan  7 17:41 America
drwxr-xr-x 2 root root    280 Jan  7 17:41 Antarctica
drwxr-xr-x 2 root root     60 Jan  7 17:41 Arctic
drwxr-xr-x 2 root root   2020 Jan  7 17:41 Asia
drwxr-xr-x 2 root root    280 Jan  7 17:41 Atlantic
drwxr-xr-x 2 root root    500 Jan  7 17:41 Australia
drwxr-xr-x 2 root root    120 Jan  7 17:41 Brazil
-rw-r--r-- 1 root root   2094 Dec  3 17:19 CET
-rw-r--r-- 1 root root   2310 Dec  3 17:19 CST6CDT
drwxr-xr-x 2 root root    200 Jan  7 17:41 Canada
drwxr-xr-x 2 root root     80 Jan  7 17:41 Chile
-rw-r--r-- 1 root root   2416 Dec  3 17:19 Cuba
-rw-r--r-- 1 root root   1908 Dec  3 17:19 EET
-rw-r--r-- 1 root root    114 Dec  3 17:19 EST
-rw-r--r-- 1 root root   2310 Dec  3 17:19 EST5EDT
-rw-r--r-- 1 root root   2399 Dec  3 17:19 Egypt
-rw-r--r-- 1 root root   3492 Dec  3 17:19 Eire
drwxr-xr-x 2 root root    740 Jan  7 17:41 Etc
drwxr-xr-x 2 root root   1320 Jan  7 17:41 Europe
...
root #ls -l /usr/share/zoneinfo/Europe/
total 256
-rw-r--r-- 1 root root 2933 Dec  3 17:19 Amsterdam
-rw-r--r-- 1 root root 1742 Dec  3 17:19 Andorra
-rw-r--r-- 1 root root 1151 Dec  3 17:19 Astrakhan
-rw-r--r-- 1 root root 2262 Dec  3 17:19 Athens
-rw-r--r-- 1 root root 3664 Dec  3 17:19 Belfast
-rw-r--r-- 1 root root 1920 Dec  3 17:19 Belgrade
-rw-r--r-- 1 root root 2298 Dec  3 17:19 Berlin
-rw-r--r-- 1 root root 2301 Dec  3 17:19 Bratislava
-rw-r--r-- 1 root root 2933 Dec  3 17:19 Brussels
...

Suppose the timezone of choice is Europe/Brussels.

OpenRC

The desired timezone name can be written to /etc/timezone:

root #echo "Europe/Brussels" > /etc/timezone

Finally, the sys-libs/timezone-data package can be reconfigured - updating /etc/localtime, based on the /etc/timezone entry:

root #emerge --config sys-libs/timezone-data
Note
The /etc/localtime file is used by the system C library to know the timezone the system is in.

systemd

A slightly different approach is employed when using systemd. A symbolic link is generated:

root #ln -sf ../usr/share/zoneinfo/Europe/Brussels /etc/localtime

Later, when systemd is running, the timezone and related settings can be configured with the timedatectl command.

Configure locales

Note
This step does not apply to users of the musl libc. Users who do not know what that means should perform this step.

Locale generation

Most users will want to use only one or two locales on their system.

Locales specify not only the language that the user should use to interact with the system, but also the rules for sorting strings, displaying dates and times, etc. Locales are case sensitive and must be represented exactly as described. A full listing of available locales can be found in the /usr/share/i18n/SUPPORTED file.

Supported system locales must be defined in the /etc/locale.gen file.

root #nano /etc/locale.gen

The following locales are an example to get both English (United States) and German (Germany/Deutschland) with the accompanying character formats (like UTF-8).

FILE /etc/locale.genEnabling US and DE locales with the appropriate character formats
en_US ISO-8859-1
en_US.UTF-8 UTF-8
de_DE ISO-8859-1
de_DE.UTF-8 UTF-8
Warning
Many applications require least one UTF-8 locale to build properly.

The next step is to run the locale-gen command. This command generates all locales specified in the /etc/locale.gen file.

root #locale-gen

To verify that the selected locales are now available, run locale -a.

On systemd installs, localectl can be used, e.g. localectl set-locale ... or localectl list-locales.

Locale selection

Once done, it is now time to set the system-wide locale settings. Again eselect is used, now with the locale module.

With eselect locale list, the available targets are displayed:

root #eselect locale list
Available targets for the LANG variable:
  [1]  C
  [2]  C.utf8
  [3]  en_US
  [4]  en_US.iso88591
  [5]  en_US.utf8
  [6]  de_DE
  [7]  de_DE.iso88591
  [8]  de_DE.utf8
  [9] POSIX
  [ ]  (free form)

With eselect locale set <NUMBER> the correct locale can be selected:

root #eselect locale set 2

Manually, this can still be accomplished through the /etc/env.d/02locale file and for systemd the /etc/locale.conf file:

FILE /etc/env.d/02localeManually setting system locale definitions
LANG="de_DE.UTF-8"
LC_COLLATE="C.UTF-8"

Setting the locale will avoid warnings and errors during kernel and software compilations later in the installation.

Now reload the environment:

root #env-update && source /etc/profile && export PS1="(chroot) ${PS1}"

For additional guidance through the locale selection process read also the Localization guide and the UTF-8 guide.

References





Optional: Installing firmware and/or microcode

Firmware

Linux Firmware

Before getting to configuring kernel sections, it is beneficial to be aware that some hardware devices require additional, sometimes non-FOSS compliant, firmware to be installed on the system before they will operate correctly. This is often the case for wireless network interfaces commonly found in both desktop and laptop computers. Modern video chips from vendors like AMD, Nvidia, and Intel, often also require external firmware files to be fully functional. Most firmware for modern hardware devices can be found within the sys-kernel/linux-firmware package.

It is recommended to have the sys-kernel/linux-firmware package installed before the initial system reboot in order to have the firmware available in the event that it is necessary:

root #emerge --ask sys-kernel/linux-firmware
Note
Installing certain firmware packages often requires accepting the associated firmware licenses. If necessary, visit the license handling section of the Handbook for help on accepting licenses.

It is important to note that kernel symbols that are built as modules (M) will load their associated firmware files from the filesystem when they are loaded by the kernel. It is not necessary to include the device's firmware files into the kernel's binary image for symbols loaded as modules.

SOF Firmware

Sound Open Firmware (SOF) is a new open source audio driver meant to replace the proprietary Smart Sound Technology (SST) audio driver from Intel. 10th gen+ and Apollo Lake (Atom E3900, Celeron N3350, and Pentium N4200) Intel CPUs require this firmware for certain features and certain AMD APUs also have support for this firmware. SOF's supported platforms matrix can be found here for more information.

root #emerge --ask sys-firmware/sof-firmware

Microcode

In addition to discrete graphics hardware and network interfaces, CPUs also can require firmware updates. Typically this kind of firmware is referred to as microcode. Newer revisions of microcode are sometimes necessary to patch instability, security concerns, or other miscellaneous bugs in CPU hardware.

Microcode updates for AMD CPUs are distributed within the aforementioned sys-kernel/linux-firmware package. Microcode for Intel CPUs can be found within the sys-firmware/intel-microcode package, which will need to be installed separately. See the Microcode article for more information on how to apply microcode updates.

Kernel configuration and compilation

Now it is time to configure and compile the kernel sources. For the purposes of the installation, three approaches to kernel management will be presented, however at any point post-installation a new approach can be employed.

Ranked from least involved to most involved:

Full automation approach: Distribution kernels
A Distribution Kernel is used to configure, automatically build, and install the Linux kernel, its associated modules, and (optionally, but enabled by default) an initramfs file. Future kernel updates are fully automated since they are handled through the package manager, just like any other system package. It is possible provide a custom kernel configuration file if customization is necessary. This is the least involved process and is perfect for new Gentoo users due to it working out-of-the-box and offering minimal involvement from the system administrator.
Full manual approach
New kernel sources are installed via the system package manager. The kernel is manually configured, built, and installed using the eselect kernel and a slew of make commands. Future kernel updates repeat the manual process of configuring, building, and installing the kernel files. This is the most involved process, but offers maximum control over the kernel update process.
Hybrid approach: Genkernel
New kernel sources are installed via the system package manager. System administrators may use Gentoo's genkernel tool to configure, build, and install the Linux kernel, its associated modules, and (optionally, but not enabled by default) an initramfs file. It is possible provide a custom kernel configuration file if customization is necessary. Future kernel configuration, compilation, and installation require the system administrator's involvement in the form of running eselect kernel, genkernel, and potentially other commands for each update.

The core around which all distributions are built is the Linux kernel. It is the layer between the user's programs and the system hardware. Although the handbook provides its users several possible kernel sources, a more comprehensive listing with more detailed descriptions is available at the Kernel overview page.

Tip
Kernel installation tasks such as, copying the kernel image to /boot or the EFI System Partition, generating an initramfs and/or Unified Kernel Image, updating bootloader configuration, can be automated with installkernel. Users may wish to configure and install sys-kernel/installkernel before proceeding. See the Kernel installation section below for more more information.

Distribution kernels

Distribution Kernels are ebuilds that cover the complete process of unpacking, configuring, compiling, and installing the kernel. The primary advantage of this method is that the kernels are updated to new versions by the package manager as part of @world upgrade. This requires no more involvement than running an emerge command. Distribution kernels default to a configuration supporting the majority of hardware, however two mechanisms are offered for customization: savedconfig and config snippets. See the project page for more details on configuration.

Installing a distribution kernel

Before installing the kernel package the dracut USE flag needs to be added for the package sys-kernel/installkernel in /etc/portage/package.use:

FILE /etc/portage/package.use/installkernelEnable dracut support
sys-kernel/installkernel dracut

Users may also wish to enable additional sys-kernel/installkernel USE flags at this stage. See the Installation/Kernel#Installkernel section for details.

To build a kernel with Gentoo patches from source, type:

root #emerge --ask sys-kernel/gentoo-kernel

System administrators who want to avoid compiling the kernel sources locally can instead use precompiled kernel images:

root #emerge --ask sys-kernel/gentoo-kernel-bin
Optional: Signed kernel modules

The kernel modules in the prebuilt distribution kernel (sys-kernel/gentoo-kernel-bin) are already signed. To sign the modules of kernels built from source enable the modules-sign USE flag, and optionally specify which key to use for signing in /etc/portage/make.conf:

FILE /etc/portage/make.confEnable module signing
USE="modules-sign"

# Optionally, to use custom signing keys.
MODULES_SIGN_KEY="/path/to/kernel_key.pem"
MODULES_SIGN_CERT="/path/to/kernel_key.pem" # Only required if the MODULES_SIGN_KEY does not also contain the certificate.
MODULES_SIGN_HASH="sha512" # Defaults to sha512.

If MODULES_SIGN_KEY is not specified the kernel build system will generate a key, it will be stored in /usr/src/linux-x.y.z/certs. It is recommended to manually generate a key to ensure that it will be the same for each kernel release. A key may be generated with:

root #openssl req -new -nodes -utf8 -sha256 -x509 -outform PEM -out kernel_key.pem -keyout kernel_key.pem
Note
The MODULES_SIGN_KEY and MODULES_SIGN_CERT may be different files. For this example the pem file generated by OpenSSL includes both the key and the accompanying certificate, and thus both variables are set to the same value.

OpenSSL will ask some questions about the user generating the key, it is recommended to fill in these questions as detailed as possible.

Store the key in a safe location, at the very least the key should be readable only by the root user. Verify this with:

root #ls -l kernel_key.pem
 -r-------- 1 root root 3164 Jan  4 10:38 kernel_key.pem 

If this outputs anything other then the above, correct the permissions with:

root #chown root:root kernel_key.pem
root #chmod 400 kernel_key.pem
Optional: Signing the kernel image (Secure Boot)

The kernel image in the prebuilt distribution kernel (sys-kernel/gentoo-kernel-bin) is already signed for use with Secure Boot. To sign the kernel image of kernels built from source enable the secureboot USE flag, and optionally specify which key to use for signing in /etc/portage/make.conf. Note that signing the kernel image for use with secureboot requires that the kernel modules are also signed, the same key may be used to sign both the kernel image and the kernel modules:

FILE /etc/portage/make.confEnable custom signing keys
USE="modules-sign secureboot"

# Optionally, to use custom signing keys.
MODULES_SIGN_KEY="/path/to/kernel_key.pem"
MODULES_SIGN_CERT="/path/to/kernel_key.pem" # Only required if the MODULES_SIGN_KEY does not also contain the certificate.
MODULES_SIGN_HASH="sha512" # Defaults to sha512.

# Optionally, to boot with secureboot enabled, may be the same or different signing key.
SECUREBOOT_SIGN_KEY="/path/to/kernel_key.pem"
SECUREBOOT_SIGN_CERT="/path/to/kernel_key.pem"
Note
The SECUREBOOT_SIGN_KEY and SECUREBOOT_SIGN_CERT may be different files. For this example the pem file generated by OpenSSL includes both the key and the accompanying certificate, and thus both variables are set to the same value.
Note
For this example the same key that was generated to sign the modules is used to sign the kernel image. It is also possible to generate and use a second separate key for signing the kernel image. The same OpenSSL command as in the previous section may be used again.

See the above section for instructions on generating a new key, the steps may be repeated if a separate key should be used to sign the kernel image.

To successfully boot with Secure Boot enabled, the used bootloader must also be signed and the certificate must be accepted by the UEFI firmware or Shim. This will be explained later in the handbook.

Upgrading and cleaning up

Once the kernel is installed, the package manager will automatically update it to newer versions. The previous versions will be kept until the package manager is requested to clean up stale packages. To reclaim disk space, stale packages can be trimmed by periodically running emerge with the --depclean option:

root #emerge --depclean

Alternatively, to specifically clean up old kernel versions:

root #emerge --prune sys-kernel/gentoo-kernel sys-kernel/gentoo-kernel-bin

Post-install/upgrade tasks

Distribution kernels are capable of rebuilding kernel modules installed by other packages. Portage provides a hook with dist-kernel USE flag which is part of linux-mod-r1.eclass and controls a subslot dependency on virtual/dist-kernel.

This USE flag should be applied globally if using a distribution kernel inside /etc/portage/make.conf. Doing so will allow packages such as sys-fs/zfs and x11-drivers/nvidia-drivers to automatically be rebuilt against a newly updated kernel and, if applicable, will re-generate the initramfs accordingly.

Manually rebuilding the initramfs or Unified Kernel Image

If required, manually trigger such rebuilds by, after a kernel upgrade, executing:

root #emerge --ask @module-rebuild

If any kernel modules (e.g. ZFS) are needed at early boot, rebuild the initramfs afterward via:

root #emerge --config sys-kernel/gentoo-kernel
root #emerge --config sys-kernel/gentoo-kernel-bin

Installing the kernel sources

Note
This section is only relevant when using the following genkernel (hybrid) or manual kernel management approach.

The use of sys-kernel/installkernel is not strictly required, but highly recommended. When this package is installed, the kernel installation process will be delegated to installkernel. This allows for installing several different kernel versions side-by-side as well as managing and automating several tasks relating to kernel installation described later in the handbook. Install it now with:

root #emerge --ask sys-kernel/installkernel

When installing and compiling the kernel for amd64-based systems, Gentoo recommends the sys-kernel/gentoo-sources package.

Choose an appropriate kernel source and install it using emerge:

root #emerge --ask sys-kernel/gentoo-sources

This will install the Linux kernel sources in /usr/src/ using the specific kernel version in the path. It will not create a symbolic link by itself without the symlink USE flag being enabled on the chosen kernel sources package.

It is conventional for a /usr/src/linux symlink to be maintained, such that it refers to whichever sources correspond with the currently running kernel. However, this symbolic link will not be created by default. An easy way to create the symbolic link is to utilize eselect's kernel module.

For further information regarding the purpose of the symlink, and how to manage it, please refer to Kernel/Upgrade.

First, list all installed kernels:

root #eselect kernel list
Available kernel symlink targets:
  [1]   linux-6.6.21-gentoo

In order to create a symbolic link called linux, use:

root #eselect kernel set 1
root #ls -l /usr/src/linux
lrwxrwxrwx    1 root   root    12 Oct 13 11:04 /usr/src/linux -> linux-6.6.21-gentoo

Alternative: Manual configuration

Introduction

Note
In case it was missed, this section requires the kernel sources to be installed. Be sure to obtain the relevant kernel sources, then return here for the rest of section.

Manually configuring a kernel is commonly seen as one of the most difficult procedures a system administrator has to perform. Nothing is less true - after configuring a few kernels no one remembers that it was difficult!

However, one thing is true: it is vital to know the system when a kernel is configured manually. Most information can be gathered by emerging sys-apps/pciutils which contains the lspci command:

root #emerge --ask sys-apps/pciutils
Note
Inside the chroot, it is safe to ignore any pcilib warnings (like pcilib: cannot open /sys/bus/pci/devices) that lspci might throw out.

Another source of system information is to run lsmod to see what kernel modules the installation CD uses as it might provide a nice hint on what to enable.

Now go to the kernel source directory and execute make menuconfig. This will fire up menu-driven configuration screen.

root #cd /usr/src/linux
root #make menuconfig

The Linux kernel configuration has many, many sections. Let's first list some options that must be activated (otherwise Gentoo will not function, or not function properly without additional tweaks). We also have a Gentoo kernel configuration guide on the Gentoo wiki that might help out further.

Enabling required options

When using sys-kernel/gentoo-sources, it is strongly recommend the Gentoo-specific configuration options be enabled. These ensure that a minimum of kernel features required for proper functioning is available:

KERNEL Enabling Gentoo-specific options
Gentoo Linux --->
  Generic Driver Options --->
    [*] Gentoo Linux support
    [*]   Linux dynamic and persistent device naming (userspace devfs) support
    [*]   Select options required by Portage features
        Support for init systems, system and service managers  --->
          [*] OpenRC, runit and other script based systems and managers
          [*] systemd

Naturally the choice in the last two lines depends on the selected init system (OpenRC vs. systemd). It does not hurt to have support for both init systems enabled.

When using sys-kernel/vanilla-sources, the additional selections for init systems will be unavailable. Enabling support is possible, but goes beyond the scope of the handbook.

Enabling support for typical system components

Make sure that every driver that is vital to the booting of the system (such as SATA controllers, NVMe block device support, filesystem support, etc.) is compiled in the kernel and not as a module, otherwise the system may not be able to boot completely.

Next select the exact processor type. It is also recommended to enable MCE features (if available) so that users are able to be notified of any hardware problems. On some architectures (such as x86_64), these errors are not printed to dmesg, but to /dev/mcelog. This requires the app-admin/mcelog package.

Also select Maintain a devtmpfs file system to mount at /dev so that critical device files are already available early in the boot process (CONFIG_DEVTMPFS and CONFIG_DEVTMPFS_MOUNT):

KERNEL Enabling devtmpfs support (CONFIG_DEVTMPFS)
Device Drivers --->
  Generic Driver Options --->
    [*] Maintain a devtmpfs filesystem to mount at /dev
    [*]   Automount devtmpfs at /dev, after the kernel mounted the rootfs

Verify SCSI disk support has been activated (CONFIG_BLK_DEV_SD):

KERNEL Enabling SCSI disk support (CONFIG_SCSI, CONFIG_BLK_DEV_SD)
Device Drivers --->
  SCSI device support  ---> 
    <*> SCSI device support
    <*> SCSI disk support
KERNEL Enabling basic SATA and PATA support (CONFIG_ATA_ACPI, CONFIG_SATA_PMP, CONFIG_SATA_AHCI, CONFIG_ATA_BMDMA, CONFIG_ATA_SFF, CONFIG_ATA_PIIX)
Device Drivers --->
  <*> Serial ATA and Parallel ATA drivers (libata)  --->
    [*] ATA ACPI Support
    [*] SATA Port Multiplier support
    <*> AHCI SATA support (ahci)
    [*] ATA BMDMA support
    [*] ATA SFF support (for legacy IDE and PATA)
    <*> Intel ESB, ICH, PIIX3, PIIX4 PATA/SATA support (ata_piix)

Verify basic NVMe support has been enabled:

KERNEL Enable basic NVMe support for Linux 4.4.x (CONFIG_BLK_DEV_NVME)
Device Drivers  --->
  <*> NVM Express block device
KERNEL Enable basic NVMe support for Linux 5.x.x (CONFIG_DEVTMPFS)
Device Drivers --->
  NVME Support --->
    <*> NVM Express block device

It does not hurt to enable the following additional NVMe support:

KERNEL Enabling additional NVMe support (CONFIG_NVME_MULTIPATH, CONFIG_NVME_MULTIPATH, CONFIG_NVME_HWMON, CONFIG_NVME_FC, CONFIG_NVME_TCP, CONFIG_NVME_TARGET, CONFIG_NVME_TARGET_PASSTHRU, CONFIG_NVME_TARGET_LOOP, CONFIG_NVME_TARGET_FC, CONFIG_NVME_TARGET_FCLOOP, CONFIG_NVME_TARGET_TCP
[*] NVMe multipath support
[*] NVMe hardware monitoring
<M> NVM Express over Fabrics FC host driver
<M> NVM Express over Fabrics TCP host driver
<M> NVMe Target support
  [*]   NVMe Target Passthrough support
  <M>   NVMe loopback device support
  <M>   NVMe over Fabrics FC target driver
  < >     NVMe over Fabrics FC Transport Loopback Test driver (NEW)
  <M>   NVMe over Fabrics TCP target support

Now go to File Systems and select support for the filesystems that will be used by the system. Do not compile the file system that is used for the root filesystem as module, otherwise the system may not be able to mount the partition. Also select Virtual memory and /proc file system. Select one or more of the following options as needed by the system:

KERNEL Enable file system support (CONFIG_EXT2_FS, CONFIG_EXT3_FS, CONFIG_EXT4_FS, CONFIG_BTRFS_FS, CONFIG_XFS_FS, CONFIG_MSDOS_FS, CONFIG_VFAT_FS, CONFIG_PROC_FS, and CONFIG_TMPFS)
File systems --->
  <*> Second extended fs support
  <*> The Extended 3 (ext3) filesystem
  <*> The Extended 4 (ext4) filesystem
  <*> Btrfs filesystem support
  <*> XFS filesystem support
  DOS/FAT/NT Filesystems  --->
    <*> MSDOS fs support
    <*> VFAT (Windows-95) fs support
  Pseudo Filesystems --->
    [*] /proc file system support
    [*] Tmpfs virtual memory file system support (former shm fs)

If PPPoE is used to connect to the Internet, or a dial-up modem, then enable the following options (CONFIG_PPP, CONFIG_PPP_ASYNC, and CONFIG_PPP_SYNC_TTY):

KERNEL Enabling PPPoE support (PPPoE, CONFIG_PPPOE, CONFIG_PPP_ASYNC, CONFIG_PPP_SYNC_TTY
Device Drivers --->
  Network device support --->
    <*> PPP (point-to-point protocol) support
    <*> PPP over Ethernet
    <*> PPP support for async serial ports
    <*> PPP support for sync tty ports

The two compression options won't harm but are not definitely needed, neither does the PPP over Ethernet option, that might only be used by ppp when configured to do kernel mode PPPoE.

Don't forget to include support in the kernel for the network (Ethernet or wireless) cards.

Most systems also have multiple cores at their disposal, so it is important to activate Symmetric multi-processing support (CONFIG_SMP):

KERNEL Activating SMP support (CONFIG_SMP)
Processor type and features  --->
  [*] Symmetric multi-processing support
Note
In multi-core systems, each core counts as one processor.

If USB input devices (like keyboard or mouse) or other USB devices will be used, do not forget to enable those as well:

KERNEL Enable USB and human input device support (CONFIG_HID_GENERIC, CONFIG_USB_HID, CONFIG_USB_SUPPORT, CONFIG_USB_XHCI_HCD, CONFIG_USB_EHCI_HCD, CONFIG_USB_OHCI_HCD, (CONFIG_HID_GENERIC, CONFIG_USB_HID, CONFIG_USB_SUPPORT, CONFIG_USB_XHCI_HCD, CONFIG_USB_EHCI_HCD, CONFIG_USB_OHCI_HCD, CONFIG_USB4)
Device Drivers --->
  HID support  --->
    -*- HID bus support
    <*>   Generic HID driver
    [*]   Battery level reporting for HID devices
      USB HID support  --->
        <*> USB HID transport layer
  [*] USB support  --->
    <*>     xHCI HCD (USB 3.0) support
    <*>     EHCI HCD (USB 2.0) support
    <*>     OHCI HCD (USB 1.1) support
  <*> Unified support for USB4 and Thunderbolt  --->

Optional: Signed kernel modules

To automatically sign the kernel modules enable CONFIG_MODULE_SIG_ALL:

KERNEL Sign kernel modules CONFIG_MODULE_SIG_ALL
[*] Enable loadable module support  
  -*-   Module signature verification    
    [*]     Automatically sign all modules    
    Which hash algorithm should modules be signed with? (Sign modules with SHA-512) --->

Optionally change the hash algorithm if desired.

To enforce that all modules are signed with a valid signature, enable CONFIG_MODULE_SIG_FORCE as well:

KERNEL Enforce signed kernel modules CONFIG_MODULE_SIG_FORCE
[*] Enable loadable module support  
  -*-   Module signature verification    
    [*]     Require modules to be validly signed
    [*]     Automatically sign all modules
    Which hash algorithm should modules be signed with? (Sign modules with SHA-512) --->

To use a custom key, specify the location of this key in CONFIG_MODULE_SIG_KEY, if unspecified the kernel build system will generate a key. It is recommended to generate one manually instead. This can be done with:

root #openssl req -new -nodes -utf8 -sha256 -x509 -outform PEM -out kernel_key.pem -keyout kernel_key.pem

OpenSSL will ask some questions about the user generating the key, it is recommended to fill in these questions as detailed as possible.

Store the key in a safe location, at the very least the key should be readable only by the root user. Verify this with:

root #ls -l kernel_key.pem
 -r-------- 1 root root 3164 Jan  4 10:38 kernel_key.pem 

If this outputs anything other then the above, correct the permissions with:

root #chown root:root kernel_key.pem
root #chmod 400 kernel_key.pem
KERNEL Specify signing key CONFIG_MODULE_SIG_KEY
-*- Cryptographic API  ---> 
  Certificates for signature checking  --->  
    (/path/to/kernel_key.pem) File name or PKCS#11 URI of module signing key

To also sign external kernel modules installed by other packages via linux-mod-r1.eclass, enable the modules-sign USE flag globally:

FILE /etc/portage/make.confEnable module signing
USE="modules-sign"

# Optionally, when using custom signing keys.
MODULES_SIGN_KEY="/path/to/kernel_key.pem"
MODULES_SIGN_CERT="/path/to/kernel_key.pem" # Only required if the MODULES_SIGN_KEY does not also contain the certificate
MODULES_SIGN_HASH="sha512" # Defaults to sha512
Note
The MODULES_SIGN_KEY and MODULES_SIGN_CERT may be different files. For this example the pem file generated by OpenSSL includes both the key and the accompanying certificate, and thus both variables are set to the same value.

Optional: Signing the kernel image (Secure Boot)

When signing the kernel image (for use on systems with Secure Boot enabled) it is recommended to set the following kernel config options:

KERNEL Lockdown for secureboot
General setup  --->
  Kexec and crash features  --->   
    [*] Enable kexec system call                                                                                          
    [*] Enable kexec file based system call                                                                               
    [*]   Verify kernel signature during kexec_file_load() syscall                                                        
    [*]     Require a valid signature in kexec_file_load() syscall                                                        
    [*]     Enable ""image"" signature verification support  

[*] Enable loadable module support  
  -*-   Module signature verification    
    [*]     Require modules to be validly signed
    [*]     Automatically sign all modules
    Which hash algorithm should modules be signed with? (Sign modules with SHA-512) --->  

Security options  ---> 
[*] Integrity subsystem   
  [*] Basic module for enforcing kernel lockdown                                                                       
  [*]   Enable lockdown LSM early in init                                                                       
        Kernel default lockdown mode (Integrity)  --->            

[*]   Digital signature verification using multiple keyrings                                                            
  [*]     Enable asymmetric keys support                                                                                     
  -*-       Require all keys on the integrity keyrings be signed                                                              
  [*]       Provide keyring for platform/firmware trusted keys                                                                
  [*]       Provide a keyring to which Machine Owner Keys may be added                                                        
  [ ]         Enforce Machine Keyring CA Restrictions

Where ""image"" is a placeholder for the architecture specific image name. These options, from the top to the bottom: enforces that the kernel image in a kexec call must be signed (kexec allows replacing the kernel in-place), enforces that kernel modules are signed, enables lockdown integrity mode (prevents modifying the kernel at runtime), and enables various keychains.

On arches that do not natively support decompressing the kernel (e.g. arm64 and riscv), the kernel must be built with its own decompressor (zboot):

KERNEL zboot CONFIG_EFI_ZBOOT
Device Drivers --->                                                                                                                           
  Firmware Drivers --->                                                                                                                       
    EFI (Extensible Firmware Interface) Support --->                                                                                               
      [*] Enable the generic EFI decompressor

After compilation of the kernel, as explained in the next section, the kernel image must be signed. First install app-crypt/sbsigntools and then sign the kernel image:

root #emerge --ask app-crypt/sbsigntools
root #sbsign /usr/src/linux-x.y.z/path/to/kernel-image --cert /path/to/kernel_key.pem --key /path/to/kernel_key.pem --out /usr/src/linux-x.y.z/path/to/kernel-image
Note
For this example the same key that was generated to sign the modules is used to sign the kernel image. It is also possible to generate and use a second sperate key for signing the kernel image. The same OpenSSL command as in the previous section may be used again.

Then proceed with the installation.

To automatically sign EFI executables installed by other packages, enable the secureboot USE flag globally:

FILE /etc/portage/make.confEnable Secure Boot
USE="modules-sign secureboot"

# Optionally, to use custom signing keys.
MODULES_SIGN_KEY="/path/to/kernel_key.pem"
MODULES_SIGN_CERT="/path/to/kernel_key.pem" # Only required if the MODULES_SIGN_KEY does not also contain the certificate.
MODULES_SIGN_HASH="sha512" # Defaults to sha512

# Optionally, to boot with secureboot enabled, may be the same or different signing key.
SECUREBOOT_SIGN_KEY="/path/to/kernel_key.pem"
SECUREBOOT_SIGN_CERT="/path/to/kernel_key.pem"
Note
The SECUREBOOT_SIGN_KEY and SECUREBOOT_SIGN_CERT may be different files. For this example the pem file generated by OpenSSL includes both the key and the accompanying certificate, and thus both variables are set to the same value.
Note
When generating an Unified Kernel Image with systemd's ukify the kernel image will be signed automatically before inclusion in the unified kernel image and it is not necessary to sign it manually.


Architecture specific kernel configuration

Make sure to select IA32 Emulation and 32-bit time_t if 32-bit programs should be supported (CONFIG_IA32_EMULATION and CONFIG_COMPAT_32BIT_TIME). Gentoo installs a multilib system (mixed 32-bit/64-bit computing) by default, so unless a no-multilib profile is used, these options are required.

KERNEL Selecting processor types and features
Processor type and features  --->
   [ ] Machine Check / overheating reporting 
   [ ]   Intel MCE Features
   [ ]   AMD MCE Features
   Processor family (AMD-Opteron/Athlon64)  --->
      ( ) Opteron/Athlon64/Hammer/K8
      ( ) Intel P4 / older Netburst based Xeon
      ( ) Core 2/newer Xeon
      ( ) Intel Atom
      ( ) Generic-x86-64
Binary Emulations --->
   [*] IA32 Emulation
General architecture-dependent options  --->
   [*] Provide system calls for 32-bit time_t

Enable GPT partition label support if that was used previously when partitioning the disk (CONFIG_PARTITION_ADVANCED and CONFIG_EFI_PARTITION):

KERNEL Enable support for GPT
-*- Enable the block layer --->
   Partition Types --->
      [*] Advanced partition selection
      [*] EFI GUID Partition support

Enable EFI stub support, EFI variables and EFI Framebuffer in the Linux kernel if UEFI is used to boot the system (CONFIG_EFI, CONFIG_EFI_STUB, CONFIG_EFI_MIXED, CONFIG_EFI_VARS, and CONFIG_FB_EFI):

KERNEL Enable support for UEFI
Processor type and features  --->
    [*] EFI runtime service support 
    [*]   EFI stub support
    [*]     EFI mixed-mode support
 
Device Drivers
    Graphics support  --->
        Frame buffer Devices  --->
            <*> Support for frame buffer devices  --->
                [*]   EFI-based Framebuffer Support

File Systems
    Pseudo filesystems  --->
        <*> EFI Variable filesystem

To enable the Kernel options for the use of SOF Firmware covered earlier:

KERNEL Enabling SOF Firmware support (CONFIG_SND_SOC_SOF_TOPLEVEL, CONFIG_SND_SOC_SOF_PCI, CONFIG_SND_SOC_SOF_ACPI, CONFIG_SND_SOC_SOF_AMD_TOPLEVEL, CONFIG_SND_SOC_SOF_INTEL_TOPLEVEL)
Device Drivers --->
  Sound card support --->
    Advanced Linux Sound Architecture --->
      <M> ALSA for SoC audio support --->
        [*] Sound Open Firmware Support --->
            <M> SOF PCI enumeration support
            <M> SOF ACPI enumeration support
            <M> SOF support for AMD audio DSPs
            [*] SOF support for Intel audio DSPs


Compiling and installing

With the configuration now done, it is time to compile and install the kernel. Exit the configuration and start the compilation process:

root #make && make modules_install
Note
It is possible to enable parallel builds using make -jX with X being an integer number of parallel tasks that the build process is allowed to launch. This is similar to the instructions about /etc/portage/make.conf earlier, with the MAKEOPTS variable.

When the kernel has finished compiling, copy the kernel image to /boot/. This is handled by the make install command:

root #make install

This command will copy the kernel image to /boot. If sys-kernel/installkernel is installed it will call /sbin/installkernel instead and delegate the kernel installation. Instead of simply copying the kernel to /boot, Installkernel installs each kernel with its version number in the file name. Additionally, installkernel provides a framework for automatically accomplishing various tasks relating to kernel installation, such as: generating an initramfs, building an Unified Kernel Image, and updating the bootloader configuration. See the next section for more details on installkernel.


Alternative: Genkernel

Note
In case it was missed, this section requires the kernel sources to be installed. Be sure to obtain the relevant kernel sources, then return here for the rest of section.

Genkernel should only be considered by users that have a required need that only Genkernel can meet, otherwise it is recommended to use the Distribution kernel or manually compile your own as it will make maintaining a Gentoo system a lot more simple. An example of why genkernel is more difficult to manage is the lack of integration with sys-kernel/installkernel. This means a user will not get the same level of automation as provided by the other methods, such as Unified Kernel Images will need to be created manually when using Genkernel.

Genkernel provides a generic kernel configuration file and will compile the kernel and initramfs, then install the resulting binaries to the appropriate locations. This results in minimal and generic hardware support for the system's first boot, and allows for additional update control and customization of the kernel's configuration in the future.

Be informed: while using genkernel to maintain the kernel provides system administrators with more update control over the system's kernel, initramfs, and other options, it will require a time and effort commitment to perform future kernel updates as new sources are released. Those looking for a hands-off approach to kernel maintenance should use a distribution kernel.

For additional clarity, it is a misconception to believe genkernel automatically generates a custom kernel configuration for the hardware on which it is run; it uses a predetermined kernel configuration that supports most generic hardware and automatically handles the make commands necessary to assemble and install the kernel, the associate modules, and the initramfs file.

Binary redistributable software license group

If the linux-firmware package has been previously installed, then skip onward to the to the installation section.

As a prerequisite, due to the firwmare USE flag being enabled by default for the sys-kernel/genkernel package, the package manager will also attempt to pull in the sys-kernel/linux-firmware package. The binary redistributable software licenses are required to be accepted before the linux-firmware will install.

This license group can be accepted system-wide for any package by adding the @BINARY-REDISTRIBUTABLE as an ACCEPT_LICENSE value in the /etc/portage/make.conf file. It can be exclusively accepted for the linux-firmware package by adding a specific inclusion via a /etc/portage/package.license/linux-firmware file.

If necessary, review the methods of accepting software licenses available in the Installing the base system chapter of the handbook, then make some changes for acceptable software licenses.

If in analysis paralysis, the following will do the trick:

root #mkdir /etc/portage/package.license
FILE /etc/portage/package.license/linux-firmwareAccept binary redistributable licenses for the linux-firmware package
sys-kernel/linux-firmware @BINARY-REDISTRIBUTABLE

Installation

Explanations and prerequisites aside, install the sys-kernel/genkernel package:

root #emerge --ask sys-kernel/genkernel

Generation

Compile the kernel sources by running genkernel all. Be aware though, as genkernel compiles a kernel that supports a wide array of hardware for differing computer architectures, this compilation may take quite a while to finish.

Warning
If the root partition/volume uses a filesystem other than ext4 or XFS, it may be necessary to manually configure the kernel using genkernel --menuconfig all to add built-in kernel support for the particular filesystem(s) (i.e. not building the filesystem as a module).
Note
Users of LVM2 should add --lvm as an argument to the genkernel command below.
root #genkernel --mountboot --install all

Once genkernel completes, a kernel and an initial ram filesystem (initramfs) will be generated and installed into the /boot directory. Associated modules will be installed into the /lib/modules directory. The initramfs will be started immediately after loading the kernel to perform hardware auto-detection (just like in the live disk image environments).

root #ls /boot/vmlinu* /boot/initramfs*
root #ls /lib/modules

Kernel installation

Installkernel

Installkernel may be used to automate, the kernel installation, initramfs generation, unified kernel image generation and/or bootloader configuration among other things. sys-kernel/installkernel implements two paths of achieving this: the traditional installkernel originating from Debian and systemd's kernel-install. Which one to choose depends, among other things, on the system's bootloader. By default systemd's kernel-install is used on systemd profiles, while the traditional installkernel is the default for other profiles.

If unsure, follow the 'Traditional layout' subsection below.

systemd-boot

When using systemd-boot (formerly gummiboot) as the bootloader, systemd's kernel-install must be used. Therefore ensure the systemd and the systemd-boot USE flags are enabled on sys-kernel/installkernel, and then install the relevant package for systemd-boot.

On OpenRC systems:

FILE /etc/portage/package.use/systemd-boot
sys-apps/systemd-utils boot kernel-install
sys-kernel/installkernel systemd systemd-boot
root #emerge --ask sys-apps/systemd-utils

On systemd systems:

FILE /etc/portage/package.use/systemd
sys-apps/systemd boot
sys-kernel/installkernel systemd-boot
root #emerge --ask sys-apps/systemd

GRUB

Users of GRUB can use either systemd's kernel-install or the traditional Debian installkernel. The systemd USE flag switches between these implementations. To automatically run grub-mkconfig when installing the kernel, enable the grub USE flag.

FILE /etc/portage/package.use/installkernel
sys-kernel/installkernel grub
root #emerge --ask sys-kernel/installkernel

Traditional layout, other bootloaders (e.g. lilo, etc.)

The traditional /boot layout (for e.g. LILO, etc.) is used by default if the grub, systemd-boot and uki USE flags are not enabled. No further action is required.


Building an initramfs

In certain cases it is necessary to build an initramfs - an initial ram-based file system. The most common reason is when important file system locations (like /usr/ or /var/) are on separate partitions. With an initramfs, these partitions can be mounted using the tools available inside the initramfs. The default configuration of the Project:Distribution Kernel requires an initramfs.

Without an initramfs, there is a risk that the system will not boot properly as the tools that are responsible for mounting the file systems require information that resides on unmounted file systems. An initramfs will pull in the necessary files into an archive which is used right after the kernel boots, but before the control is handed over to the init tool. Scripts on the initramfs will then make sure that the partitions are properly mounted before the system continues booting.

Important
If using genkernel, it should be used for both building the kernel and the initramfs. When using genkernel only for generating an initramfs, it is crucial to pass --kernel-config=/path/to/kernel.config to genkernel or the generated initramfs may not work with a manually built kernel. Note that manually built kernels go beyond the scope of support for the handbook. See the kernel configuration article for more information.

Installkernel can automatically generate an initramfs when installing the kernel if the dracut USE flag is enabled:

FILE /etc/portage/package.use/installkernel
sys-kernel/installkernel dracut

Alternatively, dracut may be called manually to generate an initramfs. Install sys-kernel/dracut first, then have it generate an initramfs:

root #emerge --ask sys-kernel/dracut
root #dracut --kver=6.6.21-gentoo

The initramfs will be stored in /boot/. The resulting file can be found by simply listing the files starting with initramfs:

root #ls /boot/initramfs*

Optional: Building an Unified Kernel Image

An Unified Kernel Image (UKI) combines, among other things, the kernel, the initramfs and the kernel command line into a single executable. Since the kernel command line is embedded into the unified kernel image it should be specified before generating the unified kernel image (see below). Note that any kernel command line arguments supplied by the bootloader or firmware at boot are ignored when booting with secure boot enabled.

An unified kernel image requires a stub loader, currently the only one available is systemd-stub. To enable it:

For systemd systems:

FILE /etc/portage/package.use/systemd
sys-apps/systemd boot

For OpenRC systems:

FILE /etc/portage/package.use/systemd-utils
sys-apps/systemd-utils boot kernel-install

Installkernel can automatically generate an unified kernel image using either dracut or ukify, by enabling the respective flag. The uki USE flag should be enabled as well to install the generated unified kernel image to the $ESP/EFI/Linux directory on the EFI system partition (ESP).

For dracut:

FILE /etc/portage/package.use/installkernel
sys-kernel/installkernel dracut uki
FILE /etc/dracut.conf
uefi="yes"
kernel_cmdline="some-kernel-command-line-arguments"

For ukify:

FILE /etc/portage/package.use/installkernel
sys-apps/systemd ukify          # For systemd systems
sys-apps/systemd-utils ukify    # For OpenRC systems
sys-kernel/installkernel dracut ukify uki
FILE /etc/kernel/cmdline
some-kernel-command-line-arguments

Note that while dracut can generate both an initramfs and an unified kernel image, ukify can only generate the latter and therefore the initramfs must be generated separately with dracut.

Generic Unified Kernel Image

The prebuilt sys-kernel/gentoo-kernel-bin can optionally install a prebuilt generic unified kernel image containing a generic initramfs that is able to boot most systemd based systems. It can be installed by enabling the generic-uki USE flag, and configuring installkernel to not generate a custom initramfs or unified kernel image:

FILE /etc/portage/package.use/generic-uki
sys-kernel/gentoo-kernel-bin generic-uki
sys-kernel/installkernel -dracut -ukify uki

Secure Boot

The generic Unified Kernel Image optionally distributed by sys-kernel/gentoo-kernel-bin is already pre-signed. How to sign a locally generated unified kernel image depends on whether dracut or ukify is used. Note that the location of the key and certificate should be the same as the SECUREBOOT_SIGN_KEY and SECUREBOOT_SIGN_CERT as specified in /etc/portage/make.conf.

For dracut:

FILE /etc/dracut.conf
uefi="yes"
kernel_cmdline="some-kernel-command-line-arguments"
uefi_secureboot_key="/path/to/kernel_key.pem"
uefi_secureboot_cert="/path/to/kernel_key.pem"

For ukify:

FILE /etc/kernel/uki.conf
[UKI]
SecureBootPrivateKey=/path/to/kernel_key.pem
SecureBootCertificate=/path/to/kernel_key.pem

Rebuilding external kernel modules

External kernel modules installed by other packages via linux-mod-r1.eclass must be rebuilt for each new kernel version. When the distribution kernels are used this may be automated by enabling the dist-kernel flag globally.

FILE /etc/portage/package.use/module-rebuild
*/* dist-kernel

External kernel modules may also be rebuilt manually with:

root #emerge --ask @module-rebuild

Kernel modules

Listing available kernel modules

Note
Hardware modules are optional to be listed manually. udev will normally load all hardware modules that are detected to be connected in most cases. However, it is not harmful for modules that will be automatically loaded to be listed. Modules cannot be loaded twice; they are either loaded or unloaded. Sometimes exotic hardware requires help to load their drivers.

The modules that need to be loaded during each boot in can be added to /etc/modules-load.d/*.conf files in the format of one module per line. When extra options are needed for the modules, they should be set in /etc/modprobe.d/*.conf files instead.

To view all modules available for a specific kernel version, issue the following find command. Do not forget to substitute "<kernel version>" with the appropriate version of the kernel to search:

root #find /lib/modules/<kernel version>/ -type f -iname '*.o' -or -iname '*.ko' | less

Force loading particular kernel modules

To force load the kernel to load the 3c59x.ko module (which is the driver for a specific 3Com network card family), edit the /etc/modules-load.d/network.conf file and enter the module name within it.

root #mkdir -p /etc/modules-load.d
root #nano -w /etc/modules-load.d/network.conf

Note that the module's .ko file suffix is insignificant to the loading mechanism and left out of the configuration file:

FILE /etc/modules-load.d/network.confForce loading 3c59x module
3c59x

Continue the installation with Configuring the system.





Filesystem information

Filesystem labels and UUIDs

Both MBR (BIOS) and GPT include support for filesystem labels and filesystem UUIDs. These attributes can be defined in /etc/fstab as alternatives for the mount command to use when attempting to find and mount block devices. Filesystem labels and UUIDs are identified by the LABEL and UUID prefix and can be viewed with the blkid command:

root #blkid
Warning
If the filesystem inside a partition is wiped, then the filesystem label and the UUID values will be subsequently altered or removed.

Because of uniqueness, readers that are using an MBR-style partition table are recommended to use UUIDs over labels to define mountable volumes in /etc/fstab.

Important
UUIDs of the filesystem on a LVM volume and its LVM snapshots are identical, therefore using UUIDs to mount LVM volumes should be avoided.

Partition labels and UUIDs

Systems with GPT disklabel support offer additional 'robust' options to define partitions in /etc/fstab. Partition labels and partition UUIDs can be used to identify the block device's individual partition(s), regardless of what filesystem has been chosen for the partition itself. Partition labels and UUIDs are identified by the PARTLABEL and/or PARTUUID prefixes and can be viewed nicely in the terminal by running the blkid command.

Output for an amd64 EFI system using the Discoverable Partition Specification UUIDs may like the following:

root #blkid
/dev/sr0: BLOCK_SIZE="2048" UUID="2023-08-28-03-54-40-00" LABEL="ISOIMAGE" TYPE="iso9660" PTTYPE="PMBR"
/dev/loop0: TYPE="squashfs"
/dev/sda2: PARTUUID="0657fd6d-a4ab-43c4-84e5-0933c84b4f4f"
/dev/sda3: PARTUUID="1cdf763a-5b4c-4dbf-99db-a056c504e8b2"
/dev/sda1: PARTUUID="c12a7328-f81f-11d2-ba4b-00a0c93ec93b"

While not always true for partition labels, using a UUID to identify a partition in fstab provides a guarantee that the bootloader will not be confused when looking for a certain volume, even if the filesystem is changed or re-written in the future. Using the older default block device files (/dev/sd*N) for defining the partitions in fstab is risky for systems that have SATA block devices regularly added or removed.

The naming for block device files depends on a number of factors, including how and in what order the disks are attached to the system. They also could show up in a different order depending on which of the devices are detected by the kernel first during the early boot process. With this being stated, unless the system administrator intends to constantly fiddle with the disk ordering, using default block device files is a simple and straightforward approach.

About fstab

Under Linux, all partitions used by the system must be listed in /etc/fstab. This file contains the mount points of those partitions (where they are seen in the file system structure), how they should be mounted and with what special options (automatically or not, whether users can mount them or not, etc.)

Creating the fstab file

Note
If the init system being used is systemd, the partition UUIDs conform to the Discoverable Partition Specification as given in Preparing the disks, and the system uses UEFI, then creating an fstab can be skipped, since systemd auto-mounts partitions that follow the spec.

The /etc/fstab file uses a table-like syntax. Every line consists of six fields, separated by whitespace (space(s), tabs, or a mixture of the two). Each field has its own meaning:

  1. The first field shows the block special device or remote filesystem to be mounted. Several kinds of device identifiers are available for block special device nodes, including paths to device files, filesystem labels and UUIDs, and partition labels and UUIDs.
  2. The second field shows the mount point at which the partition should be mounted.
  3. The third field shows the type of filesystem used by the partition.
  4. The fourth field shows the mount options used by mount when it wants to mount the partition. As every filesystem has its own mount options, so system admins are encouraged to read the mount man page (man mount) for a full listing. Multiple mount options are comma-separated.
  5. The fifth field is used by dump to determine if the partition needs to be dumped or not. This can generally be left as 0 (zero).
  6. The sixth field is used by fsck to determine the order in which filesystems should be checked if the system wasn't shut down properly. The root filesystem should have 1 while the rest should have 2 (or 0 if a filesystem check is not necessary).
Important
The default /etc/fstab file provided in Gentoo stage files is not a valid fstab file but instead a template that can be used to enter in relevant values.
root #nano /etc/fstab

DOS/Legacy BIOS systems

Let us take a look at how to write down the options for the /boot partition. This is just an example, and should be modified according to the partitioning decisions made earlier in the installation. In the amd64 partitioning example, /boot is usually the /dev/sda1 partition, with xfs recommended for the filesystem. It needs to be checked during boot, so we would write down:

FILE /etc/fstabAn example DOS/Legacy BIOS boot line for /etc/fstab
# Adjust for any formatting differences and/or additional partitions created from the "Preparing the disks" step
/dev/sda1   /boot     xfs    defaults        0 2

Some system administrators want the /boot partition to be mounted automatically to improve their system's security. Those people should substitute the defaults with noauto. This does mean that those users will need to manually mount this partition every time they want to use it.

Add the rules that match the previously decided partitioning scheme and append rules for devices such as CD-ROM drive(s), and of course, if other partitions or drives are used, for those too.

Below is a more elaborate example of an /etc/fstab file:


FILE /etc/fstabA full /etc/fstab example for a DOS/Legacy BIOS system
# Adjust for any formatting differences and/or additional partitions created from the "Preparing the disks" step
/dev/sda1   /boot        xfs    defaults    0 2
/dev/sda2   none         swap    sw                   0 0
/dev/sda3   /            xfs    defaults,noatime              0 1

/dev/cdrom  /mnt/cdrom   auto    noauto,user          0 0

UEFI systems

Below is an example of an /etc/fstab file for a system that will boot via UEFI firmware:


FILE /etc/fstabA full /etc/fstab example for an UEFI system
# Adjust for any formatting differences and/or additional partitions created from the "Preparing the disks" step
/dev/sda1   /efi        vfat    umask=0077     0 2
/dev/sda2   none         swap    sw                   0 0
/dev/sda3   /            xfs    defaults,noatime              0 1

/dev/cdrom  /mnt/cdrom   auto    noauto,user          0 0


DPS UEFI PARTUUID

Below is an example of an /etc/fstab file for a disk formatted with a GPT disklabel and Discoverable Partition Specification (DPS) UUIDs set for UEFI firmware:

FILE /etc/fstabDPS PARTUUID fstab example
# Adjust any formatting difference and additional partitions created from the "Preparing the disks" step.
# This example shows a GPT disklabel with Discoverable Partition Specification (DSP) UUID set:
PARTUUID=c12a7328-f81f-11d2-ba4b-00a0c93ec93b   /efi        vfat    umask=0077                   0 2
PARTUUID=0657fd6d-a4ab-43c4-84e5-0933c84b4f4f   none        swap    sw                           0 0
PARTUUID=4f68bce3-e8cd-4db1-96e7-fbcaf984b709   /           xfs     defaults,noatime             0 1


When auto is used in the third field, it makes the mount command guess what the filesystem would be. This is recommended for removable media as they can be created with one of many filesystems. The user option in the fourth field makes it possible for non-root users to mount the CD.

To improve performance, most users would want to add the noatime mount option, which results in a faster system since access times are not registered (those are not needed generally anyway). This is also recommended for systems with solid state drives (SSDs). Users may wish to consider lazytime instead.

Tip
Due to degradation in performance, defining the discard mount option in /etc/fstab is not recommended. It is generally better to schedule block discards on a periodic basis using a job scheduler such as cron or a timer (systemd). See Periodic fstrim jobs for more information.

Double-check the /etc/fstab file, then save and quit to continue.

Networking information

It is important to note the following sections are provided to help the reader quickly setup their system to partake in a local area network.

For systems running OpenRC, a more detailed reference for network setup is available in the advanced network configuration section, which is covered near the end of the handbook. Systems with more specific network needs may need to skip ahead, then return here to continue with the rest of the installation.

For more specific systemd network setup, please review see the networking portion of the systemd article.

Hostname

One of the choices the system administrator has to make is name their PC. This seems to be quite easy, but lots of users are having difficulties finding the appropriate name for the hostname. To speed things up, know that the decision is not final - it can be changed afterwards. In the examples below, the hostname tux is used.

Set the hostname (OpenRC or systemd)

root #echo tux > /etc/hostname

systemd

To set the system hostname for a system currently running systemd, the hostnamectl utility may be used. During the installation process however, systemd-firstboot command must be used instead (see later on in handbook).

For setting the hostname to "tux", one would run:

root #hostnamectl hostname tux

View help by running hostnamectl --help or man 1 hostnamectl.

Network

There are many options available for configuring network interfaces. This section covers a only a few methods. Choose the one which seems best suited to the setup needed.

DHCP via dhcpcd (any init system)

Most LAN networks operate a DHCP server. If this is the case, then using the dhcpcd program to obtain an IP address is recommended.

To install:

root #emerge --ask net-misc/dhcpcd

To enable and then start the service on OpenRC systems:

root #rc-update add dhcpcd default
root #rc-service dhcpcd start

To enable the service on systemd systems:

root #systemctl enable dhcpcd

With these steps completed, next time the system boots, dhcpcd should obtain an IP address from the DHCP server. See the Dhcpcd article for more details.

netifrc (OpenRC)

Tip
This is one particular way of setting up the network using Netifrc on OpenRC. Other methods exist for simpler setups like Dhcpcd.
Configuring the network

During the Gentoo Linux installation, networking was already configured. However, that was for the live environment itself and not for the installed environment. Right now, the network configuration is made for the installed Gentoo Linux system.

Note
More detailed information about networking, including advanced topics like bonding, bridging, 802.1Q VLANs or wireless networking is covered in the advanced network configuration section.

All networking information is gathered in /etc/conf.d/net. It uses a straightforward - yet perhaps not intuitive - syntax. Do not fear! Everything is explained below. A fully commented example that covers many different configurations is available in /usr/share/doc/netifrc-*/net.example.bz2.

First install net-misc/netifrc:

root #emerge --ask --noreplace net-misc/netifrc

DHCP is used by default. For DHCP to work, a DHCP client needs to be installed. This is described later in Installing Necessary System Tools.

If the network connection needs to be configured because of specific DHCP options or because DHCP is not used at all, then open /etc/conf.d/net:

root #nano /etc/conf.d/net

Set both config_eth0 and routes_eth0 to enter IP address information and routing information:

Note
This assumes that the network interface will be called eth0. This is, however, very system dependent. It is recommended to assume that the interface is named the same as the interface name when booted from the installation media if the installation media is sufficiently recent. More information can be found in the Network interface naming section.
FILE /etc/conf.d/netStatic IP definition
config_eth0="192.168.0.2 netmask 255.255.255.0 brd 192.168.0.255"
routes_eth0="default via 192.168.0.1"

To use DHCP, define config_eth0:

FILE /etc/conf.d/netDHCP definition
config_eth0="dhcp"

Please read /usr/share/doc/netifrc-*/net.example.bz2 for a list of additional configuration options. Be sure to also read up on the DHCP client man page if specific DHCP options need to be set.

If the system has several network interfaces, then repeat the above steps for config_eth1, config_eth2, etc.

Now save the configuration and exit to continue.

Automatically start networking at boot

To have the network interfaces activated at boot, they need to be added to the default runlevel.

root #cd /etc/init.d
root #ln -s net.lo net.eth0
root #rc-update add net.eth0 default

If the system has several network interfaces, then the appropriate net.* files need to be created just like we did with net.eth0.

If, after booting the system, it is discovered the network interface name (which is currently documented as eth0) was wrong, then execute the following steps to rectify:

  1. Update the /etc/conf.d/net file with the correct interface name (like enp3s0 or enp5s0, instead of eth0).
  2. Create new symbolic link (like /etc/init.d/net.enp3s0).
  3. Remove the old symbolic link (rm /etc/init.d/net.eth0).
  4. Add the new one to the default runlevel.
  5. Remove the old one using rc-update del net.eth0 default.

The hosts file

An important next step may be to inform this new system about other hosts in its network environment. Network host names can be defined in the /etc/hosts file. Adding host names here will enable host name to IP addresses resolution for hosts that are not resolved by the nameserver.

root #nano /etc/hosts
FILE /etc/hostsFilling in the networking information
# This defines the current system and must be set
127.0.0.1     tux.homenetwork tux localhost
  
# Optional definition of extra systems on the network
192.168.0.5   jenny.homenetwork jenny
192.168.0.6   benny.homenetwork benny

Save and exit the editor to continue.


System information

Root password

Set the root password using the passwd command.

root #passwd

Later an additional regular user account will be created for daily operations.

Init and boot configuration

OpenRC

When using OpenRC with Gentoo, it uses /etc/rc.conf to configure the services, startup, and shutdown of a system. Open up /etc/rc.conf and enjoy all the comments in the file. Review the settings and change where needed.

root #nano /etc/rc.conf

Next, open /etc/conf.d/keymaps to handle keyboard configuration. Edit it to configure and select the right keyboard.

root #nano /etc/conf.d/keymaps

Take special care with the keymap variable. If the wrong keymap is selected, then weird results will come up when typing on the keyboard.

Finally, edit /etc/conf.d/hwclock to set the clock options. Edit it according to personal preference.

root #nano /etc/conf.d/hwclock

If the hardware clock is not using UTC, then it is necessary to set clock="local" in the file. Otherwise the system might show clock skew behavior.

systemd

First, it is recommended to run systemd-machine-id-setup and then systemd-firstboot which will prepare various components of the system are set correctly for the first boot into the new systemd environment. The passing the following options will include a prompt for the user to set a locale, timezone, hostname, root password, and root shell values. It will also assign a random machine ID to the installation:

root #systemd-machine-id-setup
root #systemd-firstboot --prompt

Next users should run systemctl to reset all installed unit files to the preset policy values:

root #systemctl preset-all --preset-mode=enable-only

It's possible to run the full preset changes but this may reset any services which were already configured during the process:

root #systemctl preset-all

These two steps will help ensure a smooth transition from the live environment to the installation's first boot.





System logger

OpenRC

Some tools are missing from the stage3 archive because several packages provide the same functionality. It is now up to the user to choose which ones to install.

The first tool to decision is a logging mechanism for the system. Unix and Linux have an excellent history of logging capabilities - if needed, everything that happens on the system can be logged in a log file.

Gentoo offers several system logger utilities. A few of these include:

  • app-admin/sysklogd - Offers the traditional set of system logging daemons. The default logging configuration works well out of the box which makes this package a good option for beginners.
  • app-admin/syslog-ng - An advanced system logger. Requires additional configuration for anything beyond logging to one big file. More advanced users may choose this package based on its logging potential; be aware additional configuration is a necessity for any kind of smart logging.
  • app-admin/metalog - A highly-configurable system logger.

There may be other system logging utilities available through the Gentoo ebuild repository as well, since the number of available packages increases on a daily basis.

Tip
If syslog-ng is going to be used, it is recommended to install and configure logrotate. syslog-ng does not provide any rotation mechanism for the log files. Newer versions (>= 2.0) of sysklogd however handle their own log rotation.

To install the system logger of choice, emerge it. On OpenRC, add it to the default runlevel using rc-update. The following example installs and activates app-admin/sysklogd as the system's syslog utility:

root #emerge --ask app-admin/sysklogd
root #rc-update add sysklogd default

systemd

While a selection of logging mechanisms are presented for OpenRC-based systems, systemd includes a built-in logger called the systemd-journald service. The systemd-journald service is capable of handling most of the logging functionality outlined in the previous system logger section. That is to say, the majority of installations that will run systemd as the system and service manager can safely skip adding a additional syslog utilities.

See man journalctl for more details on using journalctl to query and review the systems logs.

For a number of reasons, such as the case of forwarding logs to a central host, it may be important to include redundant system logging mechanisms on a systemd-based system. This is a irregular occurrence for the handbook's typical audience and considered an advanced use case. It is therefore not covered by the handbook.

Optional: Cron daemon

OpenRC

Although it is optional and not required for every system, it is wise to install a cron daemon.

A cron daemon executes commands on scheduled intervals. Internals could be daily, weekly, or monthly, once every Tuesday, once every other week, etc. A wise system administrator will leverage the cron daemon to automate routine system maintenance tasks.

All cron daemons support high levels of granularity for scheduled tasks, and generally include the ability to send an email or other form of notification if a scheduled task does not complete as expected.

Gentoo offers several possible cron daemons, including:

  • sys-process/cronie - cronie is based on the original cron and has security and configuration enhancements like the ability to use PAM and SELinux.
  • sys-process/dcron - This lightweight cron daemon aims to be simple and secure, with just enough features to stay useful.
  • sys-process/fcron - A command scheduler with extended capabilities over cron and anacron.
  • sys-process/bcron - A younger cron system designed with secure operations in mind. To do this, the system is divided into several separate programs, each responsible for a separate task, with strictly controlled communications between parts.

cronie

The following example uses sys-process/cronie:

root #emerge --ask sys-process/cronie

Add cronie to the default system runlevel, which will automatically start it on power up:

root #rc-update add cronie default

Alternative: dcron

root #emerge --ask sys-process/dcron

If dcron is the go forward cron agent, an additional initialization command needs to be executed:

root #crontab /etc/crontab

Alternative: fcron

root #emerge --ask sys-process/fcron

If fcron is the selected scheduled task handler, an additional emerge step is required:

root #emerge --config sys-process/fcron

Alternative: bcron

bcron is a younger cron agent with built-in privilege separation.

root #emerge --ask sys-process/bcron

systemd

Similar to system logging, systemd-based systems include support for scheduled tasks out-of-the-box in the form of timers. systemd timers can run at a system-level or a user-level and include the same functionality that a traditional cron daemon would provide. Unless redundant capabilities are necessary, installing an additional task scheduler such as a cron daemon is generally unnecessary and can be safely skipped.

Optional: File indexing

In order to index the file system to provide faster file location capabilities, install sys-apps/mlocate.

root #emerge --ask sys-apps/mlocate

Optional: Remote shell access

Tip
opensshd's default configuration does not allow root to login as a remote user. Please create a non-root user and configure it appropriately to allow access post-installation if required, or adjust /etc/ssh/sshd_config to allow root.

To be able to access the system remotely after installation, sshd must be configured to start on boot.

OpenRC

To add the sshd init script to the default runlevel on OpenRC:

root #rc-update add sshd default

If serial console access is needed (which is possible in case of remote servers), agetty must be configured.

Uncomment the serial console section in /etc/inittab:

root #nano -w /etc/inittab
# SERIAL CONSOLES
s0:12345:respawn:/sbin/agetty 9600 ttyS0 vt100
s1:12345:respawn:/sbin/agetty 9600 ttyS1 vt100

systemd

To enable the SSH server, run:

root #systemctl enable sshd

To enable serial console support, run:

root #systemctl enable getty@tty1.service

Optional: Shell completion

Bash

Bash is the default shell for Gentoo systems, and therefore installing completion extensions can aid in efficiency and convenience to managing the system. The app-shells/bash-completion package will install completions available for Gentoo specific commands, as well as many other common commands and utilities:

root #emerge --ask app-shells/bash-completion

Post installation, bash completion for specific commands can managed through eselect. See the Shell completion integrations section of the bash article for more details.

Time synchronization

It is important to use some method of synchronizing the system clock. This is usually done via the NTP protocol and software. Other implementations using the NTP protocol exist, like Chrony.

To set up Chrony, for example:

root #emerge --ask net-misc/chrony

OpenRC

On OpenRC, run:

root #rc-update add chronyd default

systemd

On systemd, run:

root #systemctl enable chronyd.service

Alternatively, systemd users may wish to use the simpler systemd-timesyncd SNTP client which is installed by default.

root #systemctl enable systemd-timesyncd.service

Filesystem tools

Depending on the filesystems used, it may be necessary to install the required file system utilities (for checking the filesystem integrity, (re)formatting file systems, etc.). Note that ext4 user space tools (sys-fs/e2fsprogs are already installed as a part of the @system set.

The following table lists the tools to install if a certain filesystem tools will be needed in the installed environment.

Filesystem Package
XFS sys-fs/xfsprogs
ext4 sys-fs/e2fsprogs
VFAT (FAT32, ...) sys-fs/dosfstools
Btrfs sys-fs/btrfs-progs
ZFS sys-fs/zfs
JFS sys-fs/jfsutils

It's recommended that sys-block/io-scheduler-udev-rules is installed for the correct scheduler behavior with e.g. nvme devices:

root #emerge --ask sys-block/io-scheduler-udev-rules
Tip
For more information on filesystems in Gentoo see the filesystem article.

Networking tools

If networking was previously configured in the Configuring the system step and network setup is complete, then this 'networking tools' section can be safely skipped. In this case, proceed with the section on Configuring a bootloader.

Installing a DHCP client

Important
Most users will need a DHCP client to connect to their network. If none was installed, then the system might not be able to get on the network thus making it impossible to download a DHCP client afterwards.

A DHCP client obtains automatically an IP address for one or more network interface(s) using netifrc scripts. We recommend the use of net-misc/dhcpcd (see also dhcpcd):

root #emerge --ask net-misc/dhcpcd

Optional: Installing a PPPoE client

If PPP is used to connect to the internet, install the net-dialup/ppp package:

root #emerge --ask net-dialup/ppp

Optional: Install wireless networking tools

If the system will be connecting to wireless networks, install the net-wireless/iw package for Open or WEP networks and/or the net-wireless/wpa_supplicant package for WPA or WPA2 networks. iw is also a useful basic diagnostic tool for scanning wireless networks.

root #emerge --ask net-wireless/iw net-wireless/wpa_supplicant

Now continue with Configuring the bootloader.






Selecting a boot loader

With the Linux kernel configured, system tools installed and configuration files edited, it is time to install the last important piece of a Linux installation: the boot loader.

The boot loader is responsible for firing up the Linux kernel upon boot - without it, the system would not know how to proceed when the power button has been pressed.

For amd64, we document how to configure either GRUB or LILO for DOS/Legacy BIOS based systems, and GRUB or efibootmgr for UEFI systems.

In this section of the Handbook a delineation has been made between emerging the boot loader's package and installing a boot loader to a system disk. Here the term emerge will be used to ask Portage to make the software package available to the system. The term install will signify the boot loader copying files or physically modifying appropriate sections of the system's disk drive in order to render the boot loader activated and ready to operate on the next power cycle.

Default: GRUB

By default, the majority of Gentoo systems now rely upon GRUB (found in the sys-boot/grub package), which is the direct successor to GRUB Legacy. With no additional configuration, GRUB gladly supports older BIOS ("pc") systems. With a small amount of configuration, necessary before build time, GRUB can support more than a half a dozen additional platforms. For more information, consult the Prerequisites section of the GRUB article.

Emerge

When using an older BIOS system supporting only MBR partition tables, no additional configuration is needed in order to emerge GRUB:

root #emerge --ask --verbose sys-boot/grub

A note for UEFI users: running the above command will output the enabled GRUB_PLATFORMS values before emerging. When using UEFI capable systems, users will need to ensure GRUB_PLATFORMS="efi-64" is enabled (as it is the case by default). If that is not the case for the setup, GRUB_PLATFORMS="efi-64" will need to be added to the /etc/portage/make.conf file before emerging GRUB so that the package will be built with EFI functionality:

root #echo 'GRUB_PLATFORMS="efi-64"' >> /etc/portage/make.conf
root #emerge --ask sys-boot/grub

If GRUB was somehow emerged without enabling GRUB_PLATFORMS="efi-64", the line (as shown above) can be added to make.conf and then dependencies for the world package set can be re-calculated by passing the --update --newuse options to emerge:

root #emerge --ask --update --newuse --verbose sys-boot/grub

The GRUB software has now been merged onto the system, but it has not yet been installed as a secondary bootloader.

Install

Next, install the necessary GRUB files to the /boot/grub/ directory via the grub-install command. Presuming the first disk (the one where the system boots from) is /dev/sda, one of the following commands will do:

DOS/Legacy BIOS systems

For DOS/Legacy BIOS systems:

root #grub-install /dev/sda

UEFI systems

Important
Make sure the EFI system partition has been mounted before running grub-install. It is possible for grub-install to install the GRUB EFI file (grubx64.efi) into the wrong directory without providing any indication the wrong directory was used.

For UEFI systems:

root #grub-install --efi-directory=/efi
Installing for x86_64-efi platform.
Installation finished. No error reported.

Upon successful installation, the output should match the output of the previous command. If the output does not match exactly, then proceed to Debugging GRUB, otherwise jump to the Configure step.

Optional: Secure Boot
The information in this section has been added or modified recently and may not be as fully-tested as the rest of the documentation. If encountering documentation-related issues, please help get the issue fixed in the wiki if possible. Support is available for technical issues, if required. The wiki team is also able to help with fixing documentation.

The sys-boot/grub package does not recognize the secureboot USE flag, this is because the GRUB EFI executable is not installed during package installation, but is instead built and installed by the grub-install command via post-package installation. GRUB must therefore be manually signed after installation to the boot partition. Additionally, GRUB is a modular bootloader but loading modules is prohibited when Secure Boot is enabled. Therefore all necessary modules must be compiled into the GRUB EFI executable, below an example is shown including some basic modules, this may have to be adjusted for more advanced configurations:

root #emerge --noreplace sbsigntools
root #export GRUB_MODULES="all_video boot btrfs cat chain configfile echo efifwsetup efinet ext2 fat font gettext gfxmenu gfxterm gfxterm_background gzio halt help hfsplus iso9660 jpeg keystatus loadenv loopback linux ls lsefi lsefimmap lsefisystab lssal memdisk minicmd normal ntfs part_apple part_msdos part_gpt password_pbkdf2 png probe reboot regexp search search_fs_uuid search_fs_file search_label sleep smbios squash4 test true video xfs zfs zfscrypt zfsinfo"
root #grub-install --target=x86_64-efi --efi-directory=/efi --modules="${GRUB_MODULES}" --sbat /usr/share/grub/sbat.csv
root #sbsign /efi/EFI/Gentoo/grubx64.efi --key /path/to/kernel_key.pem --cert /path/to/kernel_key.pem --out /efi/EFI/Gentoo/grubx64.efi

To successfully boot with secure boot enabled the used certificate must either be accepted by the UEFI firmware, or shim must be used as a pre-loader. Shim is pre-signed with the third-party Microsoft Certificate, accepted by default by most UEFI motherboards.

How to configure the UEFI firmware to accept custom keys depends on the firmware vendor, which is beyond the scope of the handbook. Below is shown how to setup shim instead:

root #emerge sys-boot/shim sys-boot/mokutil sys-boot/efibootmgr
root #cp /usr/share/shim/BOOTX64.EFI /efi/EFI/Gentoo/shimx64.efi
root #cp /usr/share/shim/mmx64.efi /efi/EFI/Gentoo/mmx64.efi

Shims MOKlist requires keys in the DER format, whereas sbsign and the kernel build system expect keys in the PEM format. In the previous sections of the handbook an example was shown to generate such a signing PEM key, this key must now be converted to the DER format:

root #openssl x509 -in /path/to/kernel_key.pem -inform PEM -out /path/to/kernel_key.der -outform DER
Note
The path used here must be the path to the pem file containing the certificate belonging to the generated key. In this example both key and certificate are in the same pem file.

Then the converted certificate can be imported into Shims MOKlist, this command will ask to set some password for the import request:

root #mokutil --import /path/to/kernel_key.der
Note
When the currently booted kernel already trusts the certificate being imported, the message "Already in kernel trusted keyring." will be returned here. If this happens, re-run the above command with the argument --ignore-keyring added.

Next, register Shim with the UEFI firmware. In the following command, boot-disk and boot-partition-id must be replaced with the disk and partition identifier of the EFI system partition:

root #efibootmgr --create --disk /dev/boot-disk --part boot-partition-id --loader '\EFI\GRUB\shimx64.efi' --label 'shim' --unicode
Note
The import process will not be completed until the system is rebooted. After completing all steps in the handbook, restart the system and Shim will load, it will find the import request registered by mokutil. The MokManager application will start and ask for the password that was set when creating the import request. Follow the on-screen instructions to complete the import of the certificate, then reboot the system into the UEFI menu and enable the Secure Boot setting.
Debugging GRUB

When debugging GRUB, there are a couple of quick fixes that may result in a bootable installation without having to reboot to a new live image environment.

In the event that "EFI variables are not supported on this system" is displayed somewhere in the output, it is likely the live image was not booted in EFI mode and is presently in Legacy BIOS boot mode. The solution is to try the removable GRUB step mentioned below. This will overwrite the executable EFI file located at /EFI/BOOT/BOOTX64.EFI. Upon rebooting in EFI mode, the motherboard firmware may execute this default boot entry and execute GRUB.

If grub-install returns an error that says "Could not prepare Boot variable: Read-only file system", and the live environment was correctly booted in UEFI mode, then it should be possible to remount the efivars special mount as read-write and then re-run the aforementioned grub-install command:

root #mount -o remount,rw,nosuid,nodev,noexec --types efivarfs efivarfs /sys/firmware/efi/efivars

This is caused by certain non-official Gentoo environments not mounting the special EFI filesystem by default. If the previous command does not run, then reboot using an official Gentoo live image environment in EFI mode.

Some motherboard manufacturers with poor UEFI implementations seem to only support the /EFI/BOOT directory location for the .EFI file in the EFI System Partition (ESP). The GRUB installer can create the .EFI file in this location automatically by appending the --removable option to the install command. Ensure the ESP has been mounted before running the following command; presuming it is mounted at /efi (as defined earlier), run:

root #grub-install --target=x86_64-efi --efi-directory=/efi --removable

This creates the 'default' directory defined by the UEFI specification, and then creates a file with the default name: BOOTX64.EFI.

Configure

Next, generate the GRUB configuration based on the user configuration specified in the /etc/default/grub file and /etc/grub.d scripts. In most cases, no configuration is needed by users as GRUB will automatically detect which kernel to boot (the highest one available in /boot/) and what the root file system is. It is also possible to append kernel parameters in /etc/default/grub using the GRUB_CMDLINE_LINUX variable.

To generate the final GRUB configuration, run the grub-mkconfig command:

root #grub-mkconfig -o /boot/grub/grub.cfg
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-6.6.21-gentoo
Found initrd image: /boot/initramfs-genkernel-amd64-6.6.21-gentoo
done

The output of the command must mention that at least one Linux image is found, as those are needed to boot the system. If an initramfs is used or genkernel was used to build the kernel, the correct initrd image should be detected as well. If this is not the case, go to /boot/ and check the contents using the ls command. If the files are indeed missing, go back to the kernel configuration and installation instructions.

Tip
The os-prober utility can be used in conjunction with GRUB to detect other operating systems from attached drives. Windows 7, 8.1, 10, and other distributions of Linux are detectable. Those desiring dual boot systems should emerge the sys-boot/os-prober package then re-run the grub-mkconfig command (as seen above). If detection problems are encountered be sure to read the GRUB article in its entirety before asking the Gentoo community for support.

Alternative 1: LILO

Emerge

LILO, the LInuxLOader, is the tried and true workhorse of Linux boot loaders. However, it lacks features when compared to GRUB. LILO is still used because, on some systems, GRUB does not work and LILO does. Of course, it is also used because some people know LILO and want to stick with it. Either way, Gentoo supports both bootloaders.

Installing LILO is a breeze; just use emerge.

root #emerge --ask sys-boot/lilo

Configure

To configure LILO, first create /etc/lilo.conf:

root #nano -w /etc/lilo.conf

In the configuration file, sections are used to refer to the bootable kernel. Make sure that the kernel files (with kernel version) and initramfs files are known, as they need to be referred to in this configuration file.

Note
If the root filesystem is JFS, add an append="ro" line after each boot item since JFS needs to replay its log before it allows read-write mounting.
FILE /etc/lilo.confExample LILO configuration
boot=/dev/sda             # Install LILO in the MBR
prompt                    # Give the user the chance to select another section
timeout=50                # Wait 5 (five) seconds before booting the default section
default=gentoo            # When the timeout has passed, boot the "gentoo" section
compact                   # This drastically reduces load time and keeps the map file smaller; may fail on some systems
  
image=/boot/vmlinuz-6.6.21-gentoo
  label=gentoo            # Name we give to this section
  read-only               # Start with a read-only root. Do not alter!
  root=/dev/sda3          # Location of the root filesystem
  
image=/boot/vmlinuz-6.6.21-gentoo
  label=gentoo.rescue     # Name we give to this section
  read-only               # Start with a read-only root. Do not alter!
  root=/dev/sda3         # Location of the root filesystem
  append="init=/bin/bb"   # Launch the Gentoo static rescue shell
  
# The next two lines are for dual booting with a Windows system.
# In this example, Windows is hosted on /dev/sda6.
other=/dev/sda6
  label=windows
Note
If a different partitioning scheme and/or kernel image is used, adjust accordingly.

If an initramfs is necessary, then change the configuration by referring to this initramfs file and telling the initramfs where the root device is located:

FILE /etc/lilo.confAdding initramfs information to a boot entry
image=/boot/vmlinuz-6.6.21-gentoo
  label=gentoo
  read-only
  append="root=/dev/sda3"
  initrd=/boot/initramfs-genkernel-amd64-6.6.21-gentoo

If additional options need to be passed to the kernel, use an append statement. For instance, to add the video statement to enable framebuffer:

FILE /etc/lilo.confAdding video parameter to the boot options
image=/boot/vmlinuz-6.6.21-gentoo
  label=gentoo
  read-only
  root=/dev/sda3
  append="video=uvesafb:mtrr,ywrap,1024x768-32@85"

Users that used genkernel should know that their kernels use the same boot options as is used for the installation CD. For instance, if SCSI device support needs to be enabled, add doscsi as kernel option.

Now save the file and exit.

Install

To finish up, run the /sbin/lilo executable so LILO can apply the /etc/lilo.conf settings to the system (i.e. install itself on the disk). Keep in mind that /sbin/lilo must be executed each time a new kernel is installed or a change has been made to the lilo.conf file in order for the system to boot if the filename of the kernel has changed.

root #/sbin/lilo

Alternative 2: EFI Stub

Computer systems with UEFI-based firmware technically do not need secondary bootloaders (e.g. GRUB) in order to boot kernels. Secondary bootloaders exist to extend the functionality of UEFI firmware during the boot process. Using GRUB (see the prior section) is typically easier and more robust because it offers a more flexible approach for quickly modifying kernel parameters at boot time.

System administrators who desire to take a minimalist, although more rigid, approach to booting the system can avoid secondary bootloaders and boot the Linux kernel as an EFI stub.

The sys-boot/efibootmgr application is a tool to used interact with UEFI firmware - the system's primary bootloader. Normally this looks like adding or removing boot entries to the firmware's list of bootable entries. It can also update firmware settings so that the Linux kernels that were previously added as bootable entries can be executed with additional options. These interactions are performed through special data structures called EFI variables (hence the need for kernel support of EFI vars).

Ensure the EFI stub kernel article has been reviewed before continuing. The kernel must have specific options enabled to be directly bootable by the UEFI firmware. It may be necessary to recompile the kernel in order to build-in this support.

It is also a good idea to take a look at the efibootmgr article for additional information.

Note
To reiterate, efibootmgr is not a requirement to boot an UEFI system; it is merely necessary to add an entry for an EFI-stub kernel into the UEFI firmware. When built appropriately with EFI stub support, the Linux kernel itself can be booted directly. Additional kernel command-line options can be built-in to the Linux kernel (there is a kernel configuration option called CONFIG_CMDLINE. Similarly, support for initramfs can be 'built-in' to the kernel as well.

To boot the kernel directly from the firmware, the kernel image must be present on the EFI System Partition. This may be accomplished by enabling the efistub USE flag on sys-kernel/installkernel. Given that EFI Stub booting is not guaranteed to work on every UEFI system, the USE flag is stable masked, testing keywords must be accepted for installkernel to use this feature.

FILE /etc/portage/package.accept_keywords/installkernel
sys-kernel/installkernel **
FILE /etc/portage/package.use/installkernel
sys-kernel/installkernel efistub

Then reinstall installkernel, create the /efi/EFI/Gentoo directory and reinstall the kernel:

root #emerge --ask sys-kernel/installkernel
root #mkdir -p /efi/EFI/Gentoo

For distribution kernels:

root #emerge --ask --config sys-kernel/gentoo-kernel{,-bin}

For manually managed kernels:

root #make install

Alternatively, when installkernel is not used, the kernel may be copied manually to the EFI System Partition, calling it bzImage.efi:

root #mkdir -p /efi/EFI/Gentoo
root #cp /boot/vmlinuz-* /efi/EFI/Gentoo/bzImage.efi

Install the efibootmgr software:

root #emerge --ask sys-boot/efibootmgr

Create boot entry called "Gentoo" for the freshly compiled EFI stub kernel within the UEFI firmware:

root #efibootmgr --create --disk /dev/sda --part 1 --label "gentoo" --loader "\EFI\Gentoo\bzImage.efi"
Note
The use of a backslash (\) as directory path separator is mandatory when using UEFI definitions.

If an initial RAM file system (initramfs) is used, copy it to the EFI System Partition as well, then add the proper boot option to it:

root #efibootmgr --create --disk /dev/sda --part 1 --label "gentoo" --loader "\EFI\Gentoo\bzImage.efi" --unicode "initrd=\EFI\Gentoo\initramfs.img"
Tip
Additional kernel command line options may be parsed by the firmware to the kernel by specifying them along with the initrd=... option as shown above.

With these changes done, when the system reboots, a boot entry called "gentoo" will be available.

Unified Kernel Image

If installkernel was configured to build and install unified kernel images. The unified kernel image should already be installed to the EFI/Linux directory on the EFI system partition, if this is not the case ensure the directory exists and then run the kernel installation again as described earlier in the handbook.

To add a direct boot entry for the installed unified kernel image:

root #efibootmgr --create --disk /dev/sda --part 1 --label "gentoo" --loader "\EFI\Linux\gentoo-x.y.z.efi"

Alternative 3: Syslinux

Syslinux is yet another bootloader alternative for the amd64 architecture. It supports MBR and, as of version 6.00, it supports EFI boot. PXE (network) boot and lesser-known options are also supported. Although Syslinux is a popular bootloader for many it is unsupported by the Handbook. Readers can find information on emerging and then installing this bootloader in the Syslinux article.

Alternative 4: systemd-boot

Another option is systemd-boot, which works on both OpenRC and systemd machines. It is a thin chainloader and works well with secure boot.

To install systemd-boot:

root #bootctl install
Important
Make sure the EFI system partition has been mounted before running bootctl install.

When using this bootloader, before rebooting, verify that a new bootable entry exists using:

root #bootctl list

If no new entry exists, ensure the sys-kernel/installkernel package has been installed with the systemd-boot USE flag enabled, and re-run the kernel installation.

For the distribution kernels:

root #emerge --ask --config sys-kernel/gentoo-kernel

For a manually configured and compiled kernel:

root #make install
Important
When installing kernels for systemd-boot, no root= kernel command line argument is added by default. On systemd systems that are using an initramfs users may rely instead on systemd-gpt-auto-generator to automatically find the root partition at boot. Otherwise users should manually specify the location of the root partition by setting root= in /etc/kernel/cmdline as well as any other kernel command line arguments that should be used. And then reinstalling the kernel as described above.

Optional: Secure Boot

When the secureboot USE flag is enabled, the systemd-boot EFI executable will be signed automatically. bootctl install will automatically install the signed version.

To successfully boot with secure boot enabled the used certificate must either be accepted by the UEFI firmware, or shim must be used as a pre-loader. Shim is pre-signed with the third-party Microsoft Certificate, accepted by default by most UEFI motherboards.

How to configure the UEFI firmware to accept custom keys depends on the firmware vendor, which is beyond the scope of the handbook. A postinst hook to automatically update systemd-boot and set it up with shim instead is provided on the systemd-boot wiki page. However the first time this should be done manually by following the steps below:

root #emerge --ask sys-boot/shim sys-boot/mokutil sys-boot/efibootmgr
root #cp /usr/share/shim/BOOTX64.EFI /efi/EFI/BOOT/BOOTX64.EFI
root #cp /usr/share/shim/mmx64.efi /efi/EFI/BOOT/mmx64.efi
root #cp /efi/EFI/systemd/systemd-bootx64.efi /efi/EFI/BOOT/grubx64.efi
Note
Shim is hardcoded to load grubx64.efi. As such the systemd-boot bootloader must be named as if it were GRUB.

Shims MOKlist requires keys in the DER format, whereas sbsign and the kernel build system expect keys in the PEM format. In the previous sections of the handbook an example was shown to generate such a signing PEM key, this key must now be converted to the DER format:

root #openssl x509 -in /path/to/kernel_key.pem -inform PEM -out /path/to/kernel_key.der -outform DER
Note
The path used here must be the path to the pem file containing the certificate belonging to the generated key. In this example both key and certificate are in the same pem file.

Then the converted certificate can be imported into Shims MOKlist:

root #mokutil --import /path/to/kernel_key.der
Note
When the currently booted kernel already trusts the certificate being imported, the message "Already in kernel trusted keyring." will be returned here. If this happens, re-run the above command with the argument --ignore-keyring added.

And finally we register Shim with the UEFI firmware. In the following command, boot-disk and boot-partition-id must be replaced with the disk and partition identifier of the EFI system partition:

root #efibootmgr --create --disk /dev/boot-disk --part boot-partition-id --loader '\EFI\BOOT\BOOTX64.EFI' --label 'shim' --unicode
Note
The import process will not be completed until the system is rebooted. After completing all steps in the handbook, restart the system and Shim will load, it will find the import request registered by mokutil. The MokManager application will start and ask for the password that was set when creating the import request. Follow the on-screen instructions to complete the import of the certificate, then reboot the system into the UEFI menu and enable the Secure Boot setting.


Rebooting the system

Exit the chrooted environment and unmount all mounted partitions. Then type in that one magical command that initiates the final, true test: reboot.

(chroot) livecd #exit
livecd~#cd
livecd~#umount -l /mnt/gentoo/dev{/shm,/pts,}
livecd~#umount -R /mnt/gentoo
livecd~#reboot

Do not forget to remove the live image, otherwise it may be targeted again instead of the newly installed Gentoo system!

Once rebooted in the fresh Gentoo environment, it is wise to finish with Finalizing the Gentoo installation.





User administration

Adding a user for daily use

Working as root on a Unix/Linux system is dangerous and should be avoided as much as possible. Therefore it is strongly recommended to add one or more standard user account(s) for day-to-day use.

The groups the user is member of define what activities the user can perform. The following table lists a number of important groups:

Group Description
audio Enable the user account to access the audio devices.
cdrom Enable the user account to directly access optical devices.
cron Enable the user account to access time-based job scheduling via cron. Note: user accounts on systems running the systemd service system can use systemd timers and user service files instead of cron jobs.
floppy Enable the user account to directly access ancient mechanical devices known floppy as drives. This group is not generally used on modern systems.
games Enable the user account to able to play games. See also the video group below as well.
portage Enable the account to be able to access certain resources available to the Portage group. This is useful for Gentoo development and troubleshooting purposes.
usb Enable the user account able to access USB devices.
video Enables the user account to access video capturing hardware and hardware acceleration. See also the games group above.
wheel Enables the user account able to use the su (substitute user) command, which allows switching to the root account or other accounts. For single user systems that include a root account, it is a good idea to add this group for the primary standard user.

For instance, to create a user called larry who is a member of the wheel, users, and audio groups, log in as root first (only root can create users) and run useradd:

Login:root
Password: (Enter the root password)

When setting passwords for standard user accounts, it is good security practice to avoid using the same or a similar password as set for the root user.

Handbook authors recommended to use a password at least 16 characters in length, with a value fully unique from every other user on the system.

root #useradd -m -G users,wheel,audio -s /bin/bash larry
root #passwd larry
Password: (Enter the password for larry)
Re-enter password: (Re-enter the password to verify)

Temporarily elevating privileges

If a user ever needs to perform some task as root, they can use su - to temporarily receive root privileges. Another way is to use the sudo (app-admin/sudo) or doas (app-admin/doas) utilities which are, if correctly configured, very secure.

Disabling root login

To prevent possible threat actors from logging in as root, deleting the root password and/or disabling root login can help improve security.

To disable root login:

root #passwd -l root

To delete the root password and disable login:

root #passwd -dl root

Disk cleanup

Removing installation artifacts

With the Gentoo installation finished and the system rebooted, if everything has gone well, the stage file and other installation artifacts - such as DIGEST, CONTENT, or *.asc (PGP signature) files - can now be safely removed.

The files are located in the / directory and can be removed with the following command:

root #rm /stage3-*.tar.*

Where to go from here

Not sure where to go from here? There are many paths to explore... Gentoo provides its users with lots of possibilities and therefore has lots of documented (and less documented) features to explore here on the wiki and on other Gentoo related sub-domains (see the Gentoo online section below).

Additional documentation

It is important to note that, due to the number of choices available in Gentoo, the documentation provided by the handbook is limited in scope - it mainly focuses on the basics of getting a Gentoo system up and running and basic system management activities. The handbook intentionally excludes instructions on graphical environments, details on hardening, and other important administrative tasks. That being stated, there are more sections of the handbook to assist readers with more basic functions.

Readers should definitely take a look at the next part of the handbook entitled Working with Gentoo which explains how to keep the software up to date, install additional software packages, details on USE flags, the OpenRC init system, and various other informative topics relating to managing a Gentoo system post-installation.

Apart from the handbook, readers should also feel encouraged to explore other corners of the Gentoo wiki to find additional, community-provided documentation. The Gentoo wiki team also offers a documentation topic overview which lists a selection of wiki articles by category. For instance, it refers to the localization guide to make a system feel more at home (particularly useful for users who speak English as a second language).

The majority of users with desktop use cases will setup graphical environments in which to work natively. There are many community maintained 'meta' articles for supported desktop environments (DEs) and window managers (WMs). Readers should be aware that each DE will require slightly different setup steps, which will lengthen add complexity to bootstrapping.

Many other Meta articles exist to provide our readers with high level overviews of available software within Gentoo.

Gentoo online

Important
Readers should note that all official Gentoo sites online are governed by Gentoo's code of conduct. Being active in the Gentoo community is a privilege, not a right, and users should be aware that the code of conduct exists for a reason.

With the exception of the Libera.Chat hosted internet relay chat (IRC) network and the mailing lists, most Gentoo websites require an account on a per site basis in order to ask questions, open a discussion, or enter a bug.

Forums and IRC

Every user is welcome on our Gentoo forums or on one of our internet relay chat channels. It is easy to search for the forums to see if an issue experienced on a fresh Gentoo install has been discovered in the past and resolved after some feedback. The likelihood of other users experiencing the installation issues by first-time Gentoo can be surprising. It is advised users search the forums and the wiki before asking for assistance in Gentoo support channels.

Mailing lists

Several mailing lists are available to the community members who prefer to ask for support or feedback over email rather than create a user account on the forums or IRC. Users will need to follow the instructions in order to subscribe to specific mailing lists.

Bugs

Sometimes after reviewing the wiki, searching the forums, and seeking support in the IRC channel or mailing lists there is no known solution to a problem. Generally this is a sign to open a bug on Gentoo's Bugzilla site.

Development guide

Readers who desire to learn more about developing Gentoo can take a look at the Development guide. This guide provides instructions on writing ebuilds, working with eclasses, and provides definitions for many general concepts behind Gentoo development.

Closing thoughts

Gentoo is a robust, flexible, and excellently maintained distribution. The developer community is happy to hear feedback on how to make Gentoo an even better distribution.

As a reminder, any feedback for this handbook should follow the guidelines detailed in the How do I improve the Handbook? section at the beginning of the handbook.

We look forward to seeing how our users will choose to implement Gentoo to fit their unique use cases and needs.