Just for your information, as it *might* make things a bit simpler in the future.
I'm currently working on a kernel-maintained tmpfs-based /dev filesystem: http://git.kernel.org/?p=linux/kernel/git/kay/patches.git;a=blob;f=driver-core-devtmpfs-driver-core-maintained-dev-tmpfs.patch;hb=HEAD It would de-couple the rather complex userspace logic from a minimal working /dev, and lets current udev work on top of the kernel provided nodes, instead of being a hard requirement to have anything useful in /dev. It is intended to make things more robust and lets init=/bin/sh work with a fully populated and working /dev. The kernel will provide us a device node for every kernel device currently registered, udev would apply the policy like mode, ownership, and possibly create a different node, or delete the kernel-created one if told to do. It makes the initramfs logic much simpler and does not need a full coldplug run to bootstrap /dev. If kernel device names are used, udev does not even need to be started, and we can go straight ahead. A simple and minimal example initramfs "init", to show what's needed is below. Cheers, Kay #!/bin/sh # minimal initramfs with persistent device name support # requires devtmpfs support provided by the kernel shell() { echo "initramfs: dropping to shell" exec >/dev/console 2>&1 </dev/console < /dev/console sh -i } getarg() { local o line for o in $cmdline; do test "$o" = "$1" && return 0 if test "${o%%=*}" = "${1%=}"; then echo ${o#*=} return 0 fi done return 1 } export PATH=/sbin:/bin:/usr/sbin:/usr/bin export TERM=linux # console redirect to kernel log exec >/dev/kmsg 2>&1 </dev/console echo "initramfs: starting ..." # mount needed filesystems mount -t proc proc /proc mount -t sysfs sysfs /sys # prepare /dev mount -t devtmpfs devtmpfs /dev mkdir -m 0755 /dev/pts mkdir /dev/pts mount -t devpts -o gid=5,mode=620 devpts /dev/pts # kernel commandline read cmdline </proc/cmdline; # root we are looking for root=$(getarg root=) echo "initramfs: looking for $root" # shortcut, in case root is already there if test -e "$root"; then echo "initramfs: mounting $root" mount "$root" /root mounted=yes fi # we need to start udev to create the symlink we are looking for if test -z "$mounted"; then echo "initramfs: starting udev" udevd --daemon --resolve-names=never # create links for already existing block devices echo "initramfs: trigger block and module events" udevadm trigger --subsystem-match=block udevadm trigger --attr-match=modalias echo "initramfs: waiting for $root" # loop until root shows up while test -z "$mounted"; do if test -e "$root"; then echo "initramfs: mounting $root" mount "$root" /root && mounted=yes fi sleep 0.05 done # kill udev kill $(pidof udevd) >/dev/null 2>&1 fi # move filesystems over to the mounted root mount --move /dev /root/dev mount --move /proc /root/proc mount --move /sys /root/sys # move into root cd /root init=$(getarg init=) test -z "$init" && init=/sbin/init echo "initramfs: switching to root filesystem $root and start $init" exec run-init -c /dev/console /root $init -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
