Linux From Scratch - Version r11.2-166+

Chapitre 7. Entrée dans le chroot et construction des outils temporaires supplémentaires

7.3. Préparer les systèmes de fichiers virtuels du noyau

Applications running in user space utilize various file systems exported by the kernel to communicate with the kernel itself. These file systems are virtual: no disk space is used for them. The content of the file systems resides in memory. These file systems must be mounted in the $LFS directory tree so the applications can find them in the chroot environment.

Begin by creating directories on which the file systems will be mounted: 

mkdir -pv $LFS/{dev,proc,sys,run}

7.3.1. Monter et peupler /dev

During a normal boot of the LFS system, the kernel automatically mounts the devtmpfs filesystem on the /dev directory; the kernel creates device nodes on that virtual filesystem during the boot process or when a device is first detected or accessed. The udev daemon may change the owner or permission of the device nodes created by the kernel, or create new device nodes or symlinks to ease the work of distro maintainers or system administrators. (See Section 9.3.2.2, « Création de nœuds de périphérique » for details.) If the host kernel supports devtmpfs, we can simply mount a devtmpfs at $LFS/dev and rely on the kernel to populate it (the LFS building process does not need the additional work onto devtmpfs by udev daemon).

But, some host kernels may lack devtmpfs support and these host distros maintain the content of /dev with different methods. So the only host-agnostic way for populating $LFS/dev is bind mounting the host system's /dev directory. A bind mount is a special type of mount that allows you to create a mirror of a directory or mount point at some other location. Use the following command to do this: 

mount -v --bind /dev $LFS/dev

7.3.2. Monter les systèmes de fichiers virtuels du noyau

Montez maintenant les systèmes de fichiers virtuels du noyau restants : 

mount -v --bind /dev/pts $LFS/dev/pts
mount -vt proc proc $LFS/proc
mount -vt sysfs sysfs $LFS/sys
mount -vt tmpfs tmpfs $LFS/run

Dans certains systèmes hôtes, /dev/shm est un lien symbolique vers /run/shm. Le tmpfs /run a été monté tout à l'heure, donc vous ne devez créer un répertoire que dans ce cas précis.

In other host systems /dev/shm is a mount point for a tmpfs. In that case the mount of /dev above will only create /dev/shm as a directory in the chroot environment. In this situation we must explicitly mount a tmpfs: 

if [ -h $LFS/dev/shm ]; then
  mkdir -pv $LFS/$(readlink $LFS/dev/shm)
else
  mount -t tmpfs -o nosuid,nodev tmpfs $LFS/dev/shm
fi