local-bottom/ramroot.sh

#!/bin/sh
PREREQ=""
prereqs()
{
    echo "$PREREQ"
}

case $1 in
prereqs)
    prereqs
    exit 0
    ;;
esac

. /scripts/functions


generate_fstab()
{
    echo "# DO NOT EDIT, THIS FILE IS ON A RAM DISK!"

    # Filter out the fstab "/" entry
    while read line; do
        echo "$line" | while read FSNAME DIR OTHER; do
            case "$FSNAME" in
                ""|\#*)
                    echo "$line"
                    ;;
                *)
                    if [ "$DIR" != "/" ]; then
                        echo "$line"
                    fi
                    ;;
            esac

        done
    done

    echo "none      /       tmpfs   defaults    0   0"
}

ramroot=n
for x in $(cat /proc/cmdline); do
    case $x in
    ramroot)
        ramroot=y
        ;;
    esac
done

if [ "$ramroot" = "y" ]; then
    [ "$quiet" != "y" ] && log_begin_msg "Switching to RAMdisk root"
    umount /root
    mkdir /physroot
    mount -o ro $ROOT /physroot
    mount -t tmpfs ramroot /root
    { cd /physroot; tar c .; } | { cd /root; tar x; }
    generate_fstab < /physroot/etc/fstab > /root/etc/fstab
    umount /physroot
    rmdir /physroot
    [ "$quiet" != "y" ] && log_end_msg
fi