genkernel_fork/generic/linuxrc

#!/bin/sh
# Daniel Robbins <drobbins@gentoo.org>
# Copyright 2003 Gentoo Technologies, Inc.
# Distributed under the GPL

. /etc/initrd.defaults
. /etc/initrd.scripts

USE_DEVFS_NORMAL=1

mount -o remount,rw /
mount /proc

[ -n "$QUIET" ] && echo "0" > /proc/sys/kernel/printk

echo "${GOOD} Gentoo initrd startup..."
echo "STEP 1: Command-line parsing"
CMDLINE=`cat /proc/cmdline`
# Scan CMDLINE for any specified real_root= or cdroot arguments
for x in ${CMDLINE}
do
	case "${x}" in
		real_root\=*)
			REAL_ROOT=`parse_opt "${x}"`
		;;
		cdroot)
			CDROOT=1
			REAL_ROOT=""
		;;
		devfs)
			USE_DEVFS_NORMAL=1
		;;
		nodevfs)
			USE_DEVFS_NORMAL=0
		;;
		*)
		;;
	esac
done

# Scan CMDLINE for any "doscsi" or "noscsi"-type arguments
for x in $HWOPTS
do
	for y in $CMDLINE
	do
		if [ "$y" = "do${x}" ] 
		then
			MY_HWOPTS="MY_HWOPTS $x"
		elif [ "$y" = "no${x}" ] 
		then
			MY_HWOPTS="`echo ${MY_HWOPTS} | sed -e 's/${x}//g' -`"
		fi
	done
done

echo "STEP 2: Module loading"

# Load appropriate kernel modules
for x in $MY_HWOPTS
do
	modules_scan $x
done

echo "STEP 3: Mounting necessary filesystems per boot options"

mkdir /newroot
if [ "${CDROOT}" -eq "1" ]
then
	mount -t tmpfs tmpfs /newroot
	mkdir /newroot/dev /newroot/mnt /newroot/mnt/cdrom /newroot/mnt/.init.d /newroot/mnt/gentoo
	[ ! -e /newroot/dev/.devfsd ] && mount -t devfs devfs /newroot/dev
	devfsd /newroot/dev
	findcdmount /newroot/dev/cdroms/*
	if [ "${REAL_ROOT}" = "" ]
	then
		kill_devfsd
		umount /newroot/dev/
		umount /newroot
		# shouldn't be anything in here b/c it was on tmpfs
		rm -rf /newroot/*
		CDROOT=0
		echo "Could not find CD to boot, gonna need something else"
	fi
fi

# Don't do else b/c we set CDROOT=0 if it fails to detect
if [ "${CDROOT}" -eq "0" -a "${USE_DEVFS_NORMAL}" -eq "1" ]
then
	[ ! -e /dev/.devfsd ] && mount -t devfs devfs /dev
	devfsd /dev
fi

echo "STEP 4: Determining root device"

while true
do
	while [ "${got_good_root}" != "1" ]
	do
		
		if [ "${REAL_ROOT}" = "shell" ]
		then
			/bin/ash

			#set REAL_ROOT to "" so we get a prompt for the real root after the shell exits.
			REAL_ROOT=""
			got_good_root=0
			continue
		elif [ "${REAL_ROOT}" = "" ]
		then
			#no REAL_ROOT determined/specified. Prompt user for root block device.
			echo "Root block device unspecified or not detected."
			echo "Please specify a device to boot, or \"shell\" for a shell."
			echo -n ": "
			read REAL_ROOT
			got_good_root=0
		elif [ -b "${REAL_ROOT}" ]
		then
			got_good_root=1
		else
			REAL_ROOT=""
			got_good_root=0
		fi
	done


	if [ "${CDROOT}" -eq "1" -a "${got_good_root}" = "1" ]
	then
		break
	else
		echo "STEP 4a: Mounting root"

		mount -o rw ${REAL_ROOT} /newroot
		if [ "$?" = "0" ]
		then
			break
		else
			echo "Could not mount specified ROOT, try again"
			got_good_root=0
			REAL_ROOT=""
		fi
	fi
done

[ -n "$QUIET" ] && echo "6" > /proc/sys/kernel/printk
echo "STEP 5: Finishing up"

if [ "${CDROOT}" = "1" ]
then
	echo "STEP 5a: filling tmpfs filesystem"
	cd /newroot
	for x in ${ROOT_LINKS}
	do
		ln -s "mnt/cdrom/${x}" "${x}"
	done
	mkdir initrd proc tmp sys
	chmod 1777 tmp
	(cd /newroot/mnt/cdrom; cp -a ${ROOT_TREES} /newroot)
	kill_devfsd
else
	echo "STEP 5b: setting up stuff for pivot_root"
	mkdir -p /newroot/tmp/.initrd
fi

echo "STEP 6: pivot_root and exec/chroot real init"


cd /newroot
pivot_root . tmp/.initrd

if [ "${USE_DEVFS_NORMAL}" -eq "1" -a "${CDROOT}" -eq "0" ]
then
	# must mount a new devfs before we can
	# umount the old one for some reason
	mount -t proc proc /proc
	mount -t devfs devfs /dev
	kill_devfsd
	umount /tmp/.initrd/proc
	umount /tmp/.initrd/dev

	# Uhh, initrd is wasting memory ... let's
	# kill the sucker here and now!
	# umount tmp/.initrd
	# blockdev --flushbufs /dev/ram0

	# at this point it lets us umount the new
	# devfs, don't know why, just does, stop
	# asking questions!
	umount /dev
	umount /proc
fi

# why chroot ??  /usr/src/linux/Documentation/initrd.txt 
# says to, but I see no reason to do this .... very odd...
# here's the line it says we should do:
#       exec chroot . /sbin/init </dev/console >/dev/console 2>&1
# not gonna though ....
exec /sbin/init