Handbook:AMD64/Blocks/Booting/en

Booting the installation media
Once the installation CD is burned, it is time to boot it. Remove all external bootable media from the system (including any CD/DVD disks or USB drives), reboot the system, and enter the motherboard's firmware user interface. This is usually performed by pressing a keyboard key such as, , , or 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 external boot media.

Now place the installation CD in the CD-ROM drive and reboot. A boot prompt should be shown. At this screen, will begin the boot process with the default boot options. To boot the installation CD with custom boot options, specify a kernel followed by boot options and then hit.

At the boot prompt, users get the option of displaying the available kernels and boot options. If no choice is made within 15 seconds (either displaying information or using a kernel) then the installation CD 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).

We mentioned specifying a kernel. On the installation CD, several kernels are provided. The default one is called gentoo. Other kernels are for specific hardware needs and the -nofb variants disable framebuffer support.

The next table gives a short overview of the available kernels.

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

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 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.

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

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 +  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 +,  +  and  +. Get back to the one started on by pressing +.