initramfs script

#!/bin/busybox sh

echo "Loading, please wait..."

# /bin/mount, otherwise busybox builtin would get used
echo -n "Mounting /sys and /proc..."
/bin/mount -t sysfs -o nodev,noexec,nosuid none /sys
/bin/mount -t proc -o nodev,noexec,nosuid none /proc
echo "Done."

# Export relevant variables
export TARGET=/root

echo -n "Loading essential drivers..."
if [ -e /etc/modules ]; then
    cat /etc/modules | while read m; do
        # Skip empty lines
        if [ -z "$m" ];  then
            continue
        fi
        # Skip comments - d?ash removes whitespace prefix
        com=$(printf "%.1s" "${m}")
        if [ "$com" = "#" ]; then
            continue
        fi
        modprobe $m
    done
fi
echo "Done."

# pxelinux sets BOOTIF to 01-??-??-??-??-??-?? (MAC)
bootif_mac=""
IFS='-'
for x in ${BOOTIF} ; do
    bootif_mac="$bootif_mac:$x"
done
unset IFS
bootif_mac=${bootif_mac#:*:}

# find DEVICE to bootif_mac
for device in /sys/class/net/* ; do
    if [ -f "$device/address" ]; then
        current_mac=$(cat "$device/address")
        if [ "$bootif_mac" = "$current_mac" ]; then
            DEVICE=${device##*/}
            break
        fi
    fi
done

echo "Starting network..."

# Loopback
ifconfig lo up

# Ethernet
ifconfig ${DEVICE} up

# DHCP
udhcpc -i ${DEVICE} -q -s /sbin/setup-net

# source output of script /sbin/setup-net (HOSTNAME, SERVER)
. /tmp/net.conf

echo "Network Done."

echo -n "Mounting root file system..."

NFSOPTS="nfsvers=3,udp,nolock,retrans=10"

# mount the xino dir
/bin/mount -t tmpfs -o size=16M none /aufs/xino

# mount the clients specific dir
/bin/mount -t nfs -o rw,${NFSOPTS} ${SERVER}:/target/export/${HOSTNAME} /aufs/private

# mount the clients general dir
/bin/mount -t nfs -o ro,${NFSOPTS} ${SERVER}:/target/export/clients /aufs/clients

# mount the server root dir
/bin/mount -t nfs -o ro,${NFSOPTS} ${SERVER}:/target/ /aufs/server

# do the union
/bin/mount -t aufs -o noplink,xino=/aufs/xino/root,dirs=/aufs/private=rw:/aufs/clients=ro+wh:/aufs/server=ro none ${TARGET}

echo "Done."

# Kludge for strange aufs behaviour
# whithout this, mounted directories will be lost on command-completion
# don't ask me why this works
echo "ls /root > /dev/null"

/bin/mount --move /aufs/xino ${TARGET}/aufs/xino
/bin/mount --move /aufs/private ${TARGET}/aufs/private
/bin/mount --move /aufs/clients ${TARGET}/aufs/clients
/bin/mount --move /aufs/server ${TARGET}/aufs/server

# Move virtual filesystems over to the real filesystem
/bin/mount --move /sys ${TARGET}/sys
/bin/mount --move /proc ${TARGET}/proc

# Chain to real filesystem
exec /bin/run-init ${TARGET} /sbin/init "$@" <${TARGET}/dev/console >${TARGET}/dev/console