[systemd-devel] using /dev/root in fstab

[Samuli Suominen]

On 07/07/14 07:29, microcai wrote:
>  a long ago, /dev/root is an symblic to real root device. no matter it is on 
> NFS or HDD, we can use  
>
> /dev/root / auto defaults     0 0 
>
> in fstab to mount / as readwrite.
>
> recently, I recall this old feature, and tryed to use it, but the system 
> failed to boot, waiting for /dev/root that never come up.
>
> how to bring back the good old feature that re-use the root device assigned on 
> kernel command line ?
>

(This is ugly, I know.)

We restore the /dev/root symlink in Gentoo same way Debian is restoring
it on non-systemd
systems that still use sysvinit using a "workaround" like,

#!/bin/sh -e
#
# dev-root-link.sh: create /dev/root symlink
#
# Distributed under the terms of the GNU General Public License v2
#
# This is here because some software expects /dev/root to exist.
# For more information, see this bug:
# https://bugs.gentoo.org/show_bug.cgi?id=438380

RULESDIR=/run/udev/rules.d

[ -d $RULESDIR ] || mkdir -p $RULESDIR

eval $(udevadm info --export --export-prefix=ROOT_ --device-id-of-file=/
|| true)

[ "$ROOT_MAJOR" -a "$ROOT_MINOR" ] || exit 0

# btrfs filesystems have bogus major/minor numbers
[ "$ROOT_MAJOR" != 0 ] || exit 0

echo 'ACTION=="add|change", SUBSYSTEM=="block",
ENV{MAJOR}=="'$ROOT_MAJOR'", ENV{MINOR}=="'$ROOT_MINOR'",
SYMLINK+="root"' > $RULESDIR/61-dev-root-link.rules