Bug#975554: udev and systemd version should always be in sync

[Michael Biebl]

Am Montag, den 23.11.2020, 15:38 +0100 schrieb Ansgar:
> 
> I had installed systemd/247~rc2-2 from experimental, but kept udev at
> 246.6-2 (version currently in unstable) as it wasn't automatically
> upgraded.
> 
> This combination made various things very unhappy (possibly due to
> the
> "bind" uevents mentioned in systemd's NEWS for 247?), in particular
> dracut no longer booted.
> 
> After upgrading udev to 247~rc2-2 and regenerating the initramfs the
> system works fine again.
> 
> udev and systemd should probably be kept in sync, but I'm not sure
> how
> best to achieve this given we don't want a versioned dependency from
> systemd on udev, nor from udev on systemd.  

As mentioned in another MR [1], the imho most "elegant" way would be an
artifical libsystemd0 dependency in udev.
Breaks and Conflicts have a tendency to cause weird results, so I'd
like to avoid them as much as possible. Unfortunately, this wouldn't
help in this particular case, as pre-247 version don't already have
such a libsystemd0 dependency.

That said, I kinda appreciate the ability to test combinations of
different systemd and udev versions.



> Maybe udev should have
> "Breaks: systemd (!= ${binary:Version})"?  But I'm not sure if that
> might result in apt suggesting to remove udev instead.

Shouldn't this be the other way around, i.e. systemd having a
Breaks: udev (...) to force udev being upgraded along side.

Have you tested the other combination as well (udev 247 + systemd 246)?

v247 is a bit of a special case with the (incompatible) sticky udev
tags change. And maybe restricting it to that version is sufficient.


I guess I'd be fine if we had systemd with a Breaks: udev (<< 247~)
dependency.

I'm not sure, if we always need to enforce a lockstep upgrade.


Michael


[1] https://salsa.debian.org/systemd-team/systemd/-/merge_requests/103
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