** Changed in: linux (Ubuntu Focal)
Status: In Progress => Fix Committed
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1918427
Title:
curtin: install flash-kernel in arm64 UEFI unexpected
Status in cloud-images:
Confirmed
Status in curtin package in Ubuntu:
Confirmed
Status in linux package in Ubuntu:
Fix Released
Status in curtin source package in Focal:
New
Status in linux source package in Focal:
Fix Committed
Status in curtin source package in Hirsute:
New
Status in linux source package in Hirsute:
Fix Released
Bug description:
[Impact (linux)]
The only package that currently satisfies the bootloader Recommends
relationship on ARM systems is flash-kernel. This ignores EFI-based systems,
which will instead require GRUB. Our installers know to install GRUB anyway -
but flash-kernel also gets installed. Normally flash-kernel realizes it is not
needed and just exits - so the impact is limited to wasting space and CPU
cycles on each kernel update. However, there can be cases where calling
flash-kernel can cause problems. The original report here describes one where
flash-kernel thinks it recognizes the system and tries to run anyway, when in
fact GRUB is the correct boot loader.
[Test Case (linux)]
On an arm64 system, confirm that grub-efi-arm64 is an option in the
Recommends field:
$ apt show linux-image-unsigned-5.4.0-78-generic | grep Recommends
WARNING: apt does not have a stable CLI interface. Use with caution in
scripts.
Recommends: flash-kernel | grub-efi-arm64, initramfs-tools | linux-
initramfs-tool
[What Could Go Wrong (linux)]
First let me describe the mitigations against something going wrong. The
proposed patch was already in the hirsute kernel at the time of hirsute GA, so
it's had some real world testing, including in our installers. In addition, the
patch still leaves flash-kernel as the *default* bootloader Recommends (first
in the |'d list) - it only adds grub-efi-arm64 as a secondary option,
preventing the installation of flash-kernel if GRUB is already there.
So, the only scenario where I can see a problem might be if something
depends on flash-kernel getting installed due to a Recommends even
though GRUB is already present.
= Original Report Follows =
I used APM Mustang which flash-kernel supported in u-boot mode.
But I used it with UEFI environment.
It will cause fatal error when I used ARM64 ubuntu live server ISO to install
system.
In code[1], this will not install `flash-kernel` for APM Mustang because of
UEFI.
So that means code[2] will not disable `flash-kernel` in target system, only
disable `update-initramfs`.
When curtin execute to `install_kernel` stage, code[3,4] will not install
`flash-kernel` either.
But in code[5], it will install `linux-generic`.
`linux-generic` has a long dependency tree and it will get `flash-kernel` in
Recommended field.
Apt by default will install Recommended package before kernel is installed.[6]
So it will still execute `zz-flash-kernel` and `flash-kernel` when installing
kernel.
But system didn't create any `initrd.img` ever because curtin disable
`update-initramfs` in code[2].
This will cause that `flash-kernel` cannot find `initrd.img.<kvers>` and fail
when installing it.
This issue didn't effect all ARM64 UEFI platform because `flash-kernel`
didn't support them and skip.[7]
I'm not sure which is best solution for this.
But I think we should apply PR-27 in `flash-kernel`[8] for enhancement and
fix curtin process with this patch both.
If we only apply PR-27, it should work fine as well because it will be
skipped when detecting UEFI
and install `flash-kernel` before `disable_update_initranfs` in ARM platform
without UEFI.[9]
[Patch-1,2,3] might have side effect.
Picking one patch for curtin should be enough.
But I need your advice for this to determine which one is better for curtin.
There are two categories
1. avoid installing flash-kernel if no need, [Patch1,2]
2. always install flash-kernel in arm/arm64 and make sure it be installed
before code[2] [Patch3]
(I will attach patch in reply.)
Thanks a lot
Regards,
Date
[1]
https://github.com/canonical/curtin/blob/master/curtin/deps/__init__.py#L57-L58
[2]
https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L1693-L1699
[3]
https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L365-L370
[4]
https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L311-L327
[5]
https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L372-L374
[6] https://github.com/Debian/apt/blob/master/apt-pkg/init.cc#L132
[7]
https://salsa.debian.org/installer-team/flash-kernel/-/blob/master/functions#L787
[8] https://salsa.debian.org/installer-team/flash-kernel/-/merge_requests/27
[9] curtin will insert `flash-kernel` into `REQUIRED_EXECUTABLES` when system
is arm/arm64 without UEFI.
To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-images/+bug/1918427/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : kernel-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
