[systemd-devel] recent udev dependency change delays plymouth and udev

[Martin Pitt]

Hello all,

The recent commit
http://cgit.freedesktop.org/systemd/systemd/commit/?id=d99ce933 (which
also made it into v219-stable at
http://cgit.freedesktop.org/systemd/systemd-stable/commit/?h=v219-stable&id=b238b0eaf71)
fixed a typo in udevd's dependencies, which now results in udev
waiting for systemd-hwdb-update.service.

While this is certainly "correct" especially for stateless systems, it
is quite a bit inconvenient as it now causes a long dependency chain:

plymouth-start.service → systemd-udevd.service → systemd-hwdb-update.service →
systemd-remount-fs.service → systemd-fsck-root.service → systemd-fsckd.socket

Thus udev now does not run for a long time during early boot until the
root file system becomes checked and r/w, and also plymouth starts
very late and thus does not cover fsck/file system errors/etc. any
more. This is also very likely to break asking for cryptsetup
passphrases in plymouth?

For distros which don't yet support stateless systems (like Debian or
Ubuntu) this is rather unnecessary, especially as we handle updating
hwdb.bin through a dpkg trigger already, so it doesn't need to happen
at boot time. So I dropped this dependency again for the time being.
This isn't an ideal long-time solution, of course.

I was wondering if we could move the After=systemd-hwdb-update.service
from systemd-udevd.service to systemd-udev-trigger.service? That
should allow more stuff to run in parallel again, and we don't need to
block udevd and plymouth for so long?

Thanks,

Martin

-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)
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