27. ./init の処理 (3) dev
initramfs 内の /dev や udev の準備
# Note that this only becomes /dev on the real filesystem if udev's scripts
# are used; which they will be, but it's worth pointing out
tmpfs_size="10M"
if [ -e /etc/udev/udev.conf ]; then
. /etc/udev/udev.conf
fi
if ! mount -t devtmpfs -o mode=0755 none /dev; then
echo "W: devtmpfs not available, falling back to tmpfs for /dev"
mount -t tmpfs -o size=$tmpfs_size,mode=0755 udev /dev
[ -e /dev/console ] || mknod -m 0600 /dev/console c 5 1
[ -e /dev/null ] || mknod /dev/null c 1 3
fi
mkdir /dev/pts
mount -t devpts -o noexec,nosuid,gid=5,mode=0620 none /dev/pts || true
> /dev/.initramfs-tools
mkdir /dev/.initramfs
26/52
29. ./init (5) conf
conf ファイルの読み込み
# Bring in the main config
. /conf/initramfs.conf
for conf in conf/conf.d/*; do
[ -f ${conf} ] && . ${conf}
done
. /scripts/functions
28/52
32. ./init (6) cmdline
カーネルのコマンドライン引数 (/proc/
cmdline) の解析
# Parse command line options
for x in $(cat /proc/cmdline); do
case $x in
init=*)
init=${x#init=}
;;
root=*)
ROOT=${x#root=}
case $ROOT in
LABEL=*)
ROOT="${ROOT#LABEL=}"
(省略)
31/52
33. ./init (7) noresume
if [ -n "${noresume}" ]; then
export noresume
unset resume
else
resume=${RESUME:-}
fi
# cmdline 処理の一部:
resume=*)
RESUME="${x#resume=}"
;;
resume_offset=*)
resume_offset="${x#resume_offset=}"
;;
noresume)
noresume=y
;;
32/52
36. scripts/functions:
maybe_break (1)
# scripts/functions の一部:
maybe_break()
{
if [ "${break:-}" = "$1" ]; then
panic "Spawning shell within the initramfs"
fi
}
35/52
37. scripts/functions:
maybe_break (2)
ubuntu (lucid) の initramfs-tools
0.92bubuntu78(以降 ubuntu 版の話がある場合はこのバージョ
ン)の場合、Debian と違って複数指定可能
# scripts/functions の一部:
maybe_break()
{
if echo "${break}" | egrep -q "(,|^)$1(,|$)"; then
panic "Spawning shell within the initramfs"
fi
}
36/52
38. functions: panic (1)
起動時に root ファイルシステムが見つからなくて「(initramfs)」で止まる
ことがあるのはこれ。
# scripts/functions の一部:
panic()
{
if [ -x /sbin/usplash_write ]; then
/sbin/usplash_write "QUIT"
fi
if command -v chvt >/dev/null 2>&1; then
chvt 1
fi
# Disallow console access
if [ -n "${panic}" ]; then
sleep ${panic}
reboot
fi
modprobe i8042
modprobe atkbd
echo "$@"
REASON="$@" PS1='(initramfs) ' /bin/sh -i </dev/console >/dev/console 2>&1
}
37/52
47. ./script/local
run_scripts /scripts/local-top
のようなフックを実行したり"${ROOT}" で指
定されているデバイスをマウントしたりマウン
トできなかったときに
panic "ALERT! ${ROOT} does not exist. Dropping to a shell!"
で「(initramfs) 」のシェルに落ちたりする。
46/52
48. ./init (13) bottom
最初の方でマウントした sysfs と proc を本当
の root ファイルシステム (real root) に移動
する。
maybe_break bottom
[ "$quiet" != "y" ] && log_begin_msg "Running /scripts/init-bottom"
run_scripts /scripts/init-bottom
[ "$quiet" != "y" ] && log_end_msg
# Move virtual filesystems over to the real filesystem
mount -n -o move /sys ${rootmnt}/sys
mount -n -o move /proc ${rootmnt}/proc
47/52
49. ./init (14) check init
validate_init() {
checktarget="${1}"
# Work around absolute symlinks
if [ -d "${rootmnt}" ] && [ -h "${rootmnt}${checktarget}" ]; then
case $(readlink "${rootmnt}${checktarget}") in /*)
checktarget="$(chroot ${rootmnt} readlink ${checktarget} )"
;;
esac
fi
# Make sure the specified init can be executed
if [ ! -x "${rootmnt}${checktarget}" ]; then
return 1
fi
# Upstart uses /etc/init as configuration directory :-/
if [ -d "${rootmnt}${checktarget}" ]; then
return 1
fi
}
48/52
50. ./init (15) check init
# Check init bootarg
if [ -n "${init}" ]; then
if ! validate_init "$init"; then
echo "Target filesystem doesn't have requested ${init}."
init=
fi
fi
# Common case: /sbin/init is present
if [ ! -x "${rootmnt}/sbin/init" ]; then
# ... if it's not available search for valid init
if [ -z "${init}" ] ; then
for inittest in /sbin/init /etc/init /bin/init /bin/sh; do
if validate_init "${inittest}"; then
init="$inittest"
break
fi
done
fi
# No init on rootmount
if ! validate_init "${init}" ; then
panic "No init found. Try passing init= bootarg."
fi
fi
49/52
51. ./init (16) unsetenv
# don't leak too much of env - some init(8) don't clear it
# (keep init, rootmnt)
unset debug
unset MODPROBE_OPTIONS
unset DPKG_ARCH
unset ROOTFLAGS
unset ROOTFSTYPE
unset ROOTDELAY
unset ROOT
unset IP
unset BOOT
unset BOOTIF
unset UBIMTD
unset blacklist
unset break
unset noresume
unset panic
unset quiet
unset readonly
unset resume
unset resume_offset
50/52
52. ./init (17) exec init
klibc-utils パッケージ由来の run-init で real
root の /sbin/init などを実行
# Chain to real filesystem
exec run-init ${rootmnt} ${init} "$@"
<${rootmnt}/dev/console
>${rootmnt}/dev/console
panic "Could not execute run-init."
51/52
53. real root での処理
sysvinit
/etc/inittab に従って処理
upstart
/etc/init/*.conf に従って処理
など
Powered by Rabbit 0.6.4 52/52
![Who am I?
twitter: @znz
fingerprint
sec 4096R/B4222F7A 2010-06-27 [expires: 2040-08-10]
Key fingerprint = B863 D6DC C2B9 57B8 5238 6CE0 262E D8DB B422 2F7A
uid Kazuhiro NISHIYAMA <zn@...>
uid Kazuhiro NISHIYAMA (ZnZ) <zn@...>
uid Kazuhiro NISHIYAMA <nisiyama@...>
uid Kazuhiro NISHIYAMA (znz) <kzhr.nsym@...>
ssb 4096R/FAFB96B8 2010-06-27
1/52](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)