[Bug 2126559] Re: [SRU] Missing usb/host/xhci-pci-renesas kernel module in the initramfs

[Dave Jones]

I'll caution that the SRU template could probably do with some work
here:

The test plan checks that the fundamental change (inclusion of a missing
module) has been made, but this isn't actually checking that the
fundamental bug (inability to boot from USB) has been fixed. I
understand that in plucky's case this is going to be difficult, and also
somewhat pointless given plucky won't be seeing a new image. However, in
noble's case it would be nice to ensure this actually fixes the issue
(even if that does mean building an OS image and flashing it to USB to
do so).

The "where things could go wrong" section also needs some work. While it
correctly notes this will increase the size of the initramfs, we must
also consider what effects this may have. For example, we have had cases
where increases in the initramfs size caused boot assets to no longer
fit on the boot partition of certain devices, leading to failure to boot
on those devices. These risks should at least be mentioned (though if
the test plan is updated to actually test the boot, this risk can be
noted as being mitigated by the test plan).

Nonetheless, the patches look good, so I'm sponsoring them for plucky
and noble, but I would recommend the SRU template be updated
accordingly.

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https://bugs.launchpad.net/bugs/2126559

Title:
  [SRU] Missing usb/host/xhci-pci-renesas kernel module in the initramfs

Status in initramfs-tools package in Ubuntu:
  Fix Released
Status in initramfs-tools source package in Noble:
  Confirmed
Status in initramfs-tools source package in Plucky:
  Confirmed
Status in initramfs-tools source package in Questing:
  Fix Released

Bug description:
  [ Impact ]

   * Unable to boot from usb for specific intel hardware (GNR)
   * Especially an issue for ubuntu ISO.

  [ Fix ]

   * As done for questing, whitelist the missing module to be included in the initramfs.
   * This is a similar fix that what was done by dracut [1].

  [ Test Plan ]

   * Build an initramfs with initramfs-tools updated and check that
  drivers/usb/host/xhci-pci-renesas.ko.zst has been included

  [ Where problems could occur ]

   * Increase slightly size of the initramfs.

  [ Other info ]

   * Checked for other missing usb drivers in dracut code, nothing is
  coming up.

  1: https://github.com/dracut-ng/dracut-ng/commit/20cc20d2ac9c2908da6735b04dba49c1cb1b0bab
  __________
  On specific intel hardware (GNR), the Ubuntu ISO 24.04.3 doesn't boot when selecting the hwe kernel.
  After looking at the initrd generated, the hwe-initrd is missing kernel/drivers/usb/host/xhci-pci-renesas.ko.zst:

  $ lsinitramfs casper/initrd | grep kernel/drivers/usb/host/
  usr/lib/modules/6.8.0-71-generic/kernel/drivers/usb/host/xhci-pci-renesas.ko.zst
  usr/lib/modules/6.8.0-71-generic/kernel/drivers/usb/host/xhci-pci.ko.zst
  usr/lib/modules/6.8.0-71-generic/kernel/drivers/usb/host/xhci-plat-hcd.ko.zst
  $ lsinitramfs casper/hwe-initrd | grep kernel/drivers/usb/host/
  usr/lib/modules/6.14.0-27-generic/kernel/drivers/usb/host/xhci-plat-hcd.ko.zst

  xhci-pci module is also not there as it's in 6.14 a builtin.

  As depmod is used to find dependencies across modules, I guess it is
  missing dependencies for builtins.

  In 6.8.0 we can find in the associated modules.dep:
  kernel/drivers/usb/host/xhci-pci.ko.zst: kernel/drivers/usb/host/xhci-pci-renesas.ko.zst
  But it's not the case in 6.14.0.

  Related bug:
  - https://bugs.launchpad.net/cisco-ucs-server/+bug/2121594
  - https://bugs.launchpad.net/ubuntu/+bug/2124218

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