[Bug 2102236] Re: plucky/s390x (with root disk on dm?) does not come up after kernel update + reboot

[Frank Heimes]

Uh, good catch Nick (with that it looks like it's since oracular ?!)

And yes, the names may indeed look a bit cryptic,
since these are for s390x specific (so called CCW) devices (here in this case disk devices, but there are more types; cio-ignore is to mask out a range of CCW devices).
One difference between these CCW devices and devices on s390x, and let's say devices in the PC world is, that even if CCW devices are visible and available (means they got detected), they need to be explicitly enabled before usage - and that is what these rules are supposed to do (e.g. "chzdev -e 271d" enables DASD disk device #271d).

I vaguely remember LP#2044104, but need to re-read it to get the full details again ...
(Looks to me like this is a case on non-DPM system (that do not support auto configuration), that was not properly considered. Guess it need to somehow identified if it's an autoconfigure rule - then skip/continue - or not - then copy.)

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Title:
  plucky/s390x (with root disk on dm?) does not come up after kernel
  update + reboot

Status in Ubuntu on IBM z Systems:
  New
Status in initramfs-tools package in Ubuntu:
  New
Status in linux package in Ubuntu:
  Invalid

Bug description:
  While using the plucky daily from March 12 (that still comes with kernel 6.12)
  (and working around LP#2101831, by forcing the installation to not apply any updates)
  I get a system installed, which is at kernel level 6.12.

  Since 6.14 is out (in plucky release) since yesterday (March 12th) I tried to upgrade from 6.12 to 6.14,
  and the update itself seemed to be smooth (I couldn't find any errors while doing a full-upgrade in the terminal - see attached logs).

  But after executing a reboot, the system (in 3 different
  configurations, that use dm) does not come up again, and ends up in
  busybox, complaining that the root device couldn't be found:

  # s1lp15 FCP/SCSI multipath with LVM
  ALERT!  /dev/disk/by-id/dm-uuid-LVM-SlleSC5YA825VOM3t0KHBVFrLJcNWsnwZsObNziIB9Bk2mSVphnuTEOQ2eFiBbE1 does not exist.  Dropping to a shell!

  # s1lp15 2DASDs with LVM:
  ALERT!  /dev/disk/by-id/dm-uuid-LVM-ePTbsojYPfgMacKXwpIMNMvxk80qGzlPhRYw7DJlovmqHyla9TK6NGc70p1JN29b does not exist.  Dropping to a shell!

  # s1lp15 FCP/SCSI Multipath no LVM
  ALERT!  /dev/disk/by-id/dm-uuid-part1-mpath-36005076306ffd6b60000000000002603 does not exist.  Dropping to a shell!

  However, using a single disk without dm (so: no multipath, no lvm) the
  system is able to come up again after the reboot (after a kernel
  upgrade).

  # s1lp15 single DASD no LVM
  here the root device is:
  root=/dev/disk/by-path/ccw-0.0.260b-part1
  and it exists.

  In the 3 different cases that (that repeatedly fail) "/dev/disk/by-id"
  is missing.

  I am not sure yet what's causing this,
  it can be an issue with the device-mapper/lvm2
  but also udev rules or kernel.
  So maybe I need to add the kernel as affected component too (for now).

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