Handbook:Parts/Installation/Kernel/fr

Installer les sources
Le cœur de toute distribution est le noyau Linux. C'est la couche située entre les programmes utilisateurs et le matériel du système. Gentoo propose à ses utilisateurs plusieurs sources du noyau possibles. Une liste complète des sources, avec description, est disponible sur la page Noyau - Vue d'ensemble.

Pour les systèmes basés sur l'architecture, Gentoo recommande l'utilisation du paquet.

Choisir les sources du noyau appropriées et les installer avec :

Cela installera les sources du noyau Linux dans le répertoire, dans lequel un lien symbolique appelé pointera vers les sources du noyau installées :

Il est maintenant temps de configurer et de compiler les sources du noyau. Il y a deux façons de faire :


 * 1) Le noyau est configuré et compilé manuellement.
 * 2) Un outil appelé  est utilisé afin de configurer, compiler et installer automatiquement le noyau Linux.

La configuration manuelle est expliquée ici car elle permet une meilleur optimisation de l'environnement.

Introduction
Configurer manuellement un noyau est souvent considéré comme l'une des procédures des plus difficiles qu'un utilisateur de Linux ait à réaliser. Rien n'est mon vrai - après avoir configuré quelques noyaux, plus personne ne se rappelle que c'était difficile.

Cependant, une chose est vraie : c'est vital de connaître le système quand un noyau est configuré manuellement. La plupart des informations nécessaires peuvent être recueillies en installant le paquet qui contient la commande  :

Un autre source d'information est d'exécuter la commande pour voir quels modules du noyau sont utilisés par le média d'installation afin de savoir quoi activer plus tard.

Il est maintenant temps d'accéder au répertoire source du noyau et d'exécuter. Cela lancera un menu de configuration.

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.

Activating required options
Make sure that every driver that is vital to the booting of the system (such as SCSI controller, etc.) is compiled in the kernel and not as a module, otherwise the system will 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, but to. This requires the 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 ):

Verify SCSI disk support has been activated ( CONFIG_BLK_DEV_SD ):

Now go to File Systems and select support for the filesystems you use. Don't compile the file system that is used for the root filesystem as module, otherwise the Gentoo system will 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 ( CONFIG_EXT2_FS, CONFIG_EXT3_FS , CONFIG_EXT4_FS , CONFIG_MSDOS_FS , CONFIG_VFAT_FS , CONFIG_PROC_FS , and CONFIG_TMPFS ):

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 ):

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 ):

If USB input devices (like keyboard or mouse) or other USB devices will be used, do not forget to enable those as well ( CONFIG_HID_GENERIC and CONFIG_USB_HID, CONFIG_USB_SUPPORT , CONFIG_USB_XHCI_HCD , CONFIG_USB_EHCI_HCD , CONFIG_USB_OHCI_HCD ):

Optional: 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 or ) are on separate partitions. With an initramfs, these partitions can be mounted using the tools available inside the initramfs.

Without an initramfs, there is a huge risk that the system will not boot up properly as the tools that are responsible for mounting the file systems need information that resides on those 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.

To install an initramfs, install first, then have it generate an initramfs:

In order to enable specific support in the initramfs, such as LVM or RAID, add in the appropriate options to. See for more information. In the next example support is enabled for LVM and software RAID :

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

Now continue with Kernel modules.

Alternative: Using genkernel
If a manual configuration looks too daunting, then using is recommended. It will configure and build the kernel automatically.

works by configuring a kernel nearly identically to the way the installation CD kernel is configured. This means that when is used to build the kernel, the system will generally detect all  hardware at boot-time, just like the installation CD does. Because doesn't require any manual kernel configuration, it is an ideal solution for those users who may not be comfortable compiling their own kernels.

Now, let's see how to use genkernel. First, emerge the ebuild:

Next, edit the file so that the line containing  as second field has the first field pointing to the right device. If the partitioning example from the handbook is followed, then this device is most likely with the ext2 file system. This would make the entry in the file look like so:

Now, compile the kernel sources by running. Be aware though, as compiles a kernel that supports almost all hardware, this compilation will take quite a while to finish!

Once genkernel completes, a kernel, full set of modules and initial ram disk (initramfs) will be created. We will use the kernel and initrd when configuring a boot loader later in this document. Write down the names of the kernel and initrd as this information is used when the boot loader configuration file is edited. The initrd will be started immediately after booting to perform hardware autodetection (just like on the installation CD) before the "real" system starts up.

Configuring the modules
List the modules that need to be loaded automatically in. Extra options can be added to the modules too if necessary.

To view all available modules, run the following command. Don't forget to substitute " " with the version of the kernel just compiled:

For instance, to automatically load the module (which is the driver for a specific 3Com network card family), edit the  file and enter the module name in it.

Continue the installation with Configuring the system.

Optional: Installing firmware
Some drivers require additional firmware to be installed on the system before they work. This is often the case for network interfaces, especially wireless network interfaces. Most of the firmware is packaged in :