[Bug 1981622] Re: mtd device must be supplied (device name is empty)

[ajgreeny]

I have this problem message on both a laptop and desktop with old
spinning disks, not SSDs but both boot to a fully working OS of Xubuntu
22.04. Both machines also have fully updated Focal 20.04 versions
running,neither of which display the message.

When I was first aware of this on my laptop I did not see it on the
desktop though that had not been updated for several days. After
updating the desktop machine which included several systemd packages I
immediately started to see this on the desktop machine as well as the
laptop perhaps pointing to a link with the systemd packages?

I have also tried a 22.10 install in KVM/QEMU virtual install and that
also shows the message but also boots and runs well.

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Title:
  mtd device must be supplied (device name is empty)

Status in systemd package in Ubuntu:
  Fix Committed
Status in systemd source package in Focal:
  Confirmed
Status in systemd source package in Jammy:
  Confirmed

Bug description:
  [WORKAROUND]

  This will NOT fix a system that is not booting, because the "mtd
  device must be supplied (device name is empty)" message is not the
  cause of failed boots. This work around is only for those who are
  annoyed by the error message, but are otherwise not experiencing any
  issues.

  If you are not able to boot your system, but you see this error
  message, please open a separate bug with your journalctl and dmesg
  logs.

  # cp /{lib,etc}/systemd/system/systemd-pstore.service
  # sed -i 's/modprobe at mtdpstore.service //' /etc/systemd/system/systemd-pstore.service
  # systemctl daemon-reload

  [Impact]

  Due to mtdpstore not being properly configured as a pstore backend,
  when systemd-pstore.service tries to load the module, users get the
  following error in dmesg:

  [   18.453473] systemd[1]: Starting Load Kernel Module mtdpstore...
  [   18.462685] mtd device must be supplied (device name is empty)

  This is a distracting error for users trying to diagnose other system
  issues, especially if their system does not boot after a kernel crash
  and this is the only message displayed on the console.

  [Test Plan]

  * Force a kernel crash to populate /sys/fs/pstore, thus causing
  systemd-pstore.service to start on the subsequent boot:

  # echo 1 > /proc/sys/kernel/sysrq
  # echo 1 > /proc/sys/kernel/panic
  # echo c > /proc/sysrq-trigger

  * When the system reboots, observe the error in dmesg:

  # dmesg | grep mtd

  [Where problems could occur]

  If a system was relying on this pstore backend, and mtdpstore is built
  as a module, it is possible for systemd-pstore.service to trigger
  before mtdpstore is loaded, causing systemd-pstore to not copy the
  contents of /sys/fs/pstore. Note however that before the patched
  introduced as a result of bug 1978079, systemd-pstore.service would
  not attempt to load *any* kernel modules.

  [Original Description]

  After updating my 22.04 system (possibly caused by Systemd update).
  And now booting, dmesg has two errors:

  'mtd device must be supplied (device name is empty)'.

  See line 8 and 134 in the included logfile.

  The system are booting as it should though, and the system are working
  like it should no errors at all.

  Is this maybe caused by 'efi-pstore-not-cleared-on-boot.patch' in
  systemd?

  I have an EFI mounted at boot but it isn't used because I have
  installed my system in legacy BIOS mode.

  Is this maybe the culprit?

  I could ignore the message but it isn't nice though.

  Regards

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