Comment 2 for bug 2044104

------- Comment From <email address hidden> 2023-11-22 09:17 EDT-------
(In reply to comment #19)
> This was implemented around 2020, mainly to catch any ccw config changes in
> a user friendly way:
> https://bugs.launchpad.net/bugs/1892367
> https://i527439087.restricted.launchpadlibrarian.net/527439087/20f6c87a-829f-
> 11eb-9412-002481e91f22.txt?token=zC4n7TlCmffBDHm9Dl002PsfchDXC3Dk
>
> Regarding:
> "1) Have the generic udev initramfs script not copy zdev-generated Udev
> rules,"
> we need to be super careful here to not break stuff ...
>
> How to best identify the zdev-generated Udev rules,
> since these are not all the rules generated by chzdev (indicated by first
> line in rule), are they?

chzdev creates udev rules that can most easily be recognized via their name:
- 41-<device-type>-<device-id>.rules
- 41-cio-ignore.rules
- 40-zdev-id.rules

So a simple filter would be to skip rules named 41-*.rules on s390x in the initramfs udev hook.

As an alternative, the s390-tools zdev initramfs hook could try to delete specifically those rules with zdev:early=0 that the upstream udev hook created. While this should work correctly, it is also a kind of a workaround, where one hook adds files that another hook removes again...

If this approach is more likely to be acceptable, it could be achieved by adding something like the following to /usr/share/initramfs-tools/hooks/s390-tools-zdev:

# Remove zdev rules not intended for early boot that were copied by udev hook
chzdev --disable --persistent --by-attr zdev:early=0 \
--base "/etc/udev/rules.d/=$DESTDIR/lib/udev/rules.d/" \
--yes --quiet --no-root-update --force >/dev/null 2>&1