maas-images

Reconsider compressed kernels on arm64

Bug #1954692 reported by Julian Andres Klode on 2021-12-13

This bug affects 1 person

	Status	Importance	Assigned to
maas-images	Fix Committed	High	dann frazier
flash-kernel (Ubuntu)	Fix Released	Undecided	dann frazier
linux (Ubuntu)	Triaged	Undecided	Unassigned

Bug Description

Compressed kernel images were introduced in bug 1384955 to work around some limits on old u-boot systems. This in turn broke grub-check-signatures, meaning that while cloud images booted in secure boot, you could not upgrade grub or install new kernels on secure systems as that would trigger a "you have unsigned kernels" message. grub 2.06 also fails to boot the images, as it verifies before decompressing.

Work to fix grub to handle such images on arm64 for backward compatibility is tracked in bug 1954683. This bug is to reconsider whether the change is still necessary or could be removed in 22.04 such that we can have proper UEFI executables again.

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Related branches

~dannf/maas-images:lp1954692

Merged into maas-images:master at revision 7ddb0c263f42620777264ebfedd95519ba5b5e7e

Adam Collard (community): Approve on 2022-03-17

Revision history for this message

Julian Andres Klode (juliank) wrote on 2021-12-13:

My side question is what prevents arm64 from having the amd64 approach where AFAIUI the image is compressed but starts with a small stub that decompresses it.

Changed in linux (Ubuntu):
status:	New → Triaged

Revision history for this message

dann frazier (dannf) wrote on 2022-01-27:

0001-Introduce-Boot-Kernel-Max-Size-and-support-for-compr.patch Edit (7.7 KiB, text/plain)

@juliank my assumption is that nothing prevents it, other than someone writing that code.

Attached is a patch for flash-kernel that will handle the compression, if needed, of kernel images for the m400. One alternate solution might be to try and copy the firmware-provided device tree data into a different memory location before loading the kernel in the boot.scr script. On one hand, that would limit the changes to code that only runs on these devices. But on the other hand, the generated uImage/uInitrd files wouldn't be usable for netbooting, as I don't think there's a way to inject memory copy commands into a config file for u-boot's pxelinux emulation.

Note that we'll need to update the MAAS image generation code as well to keep that working.

Changed in flash-kernel (Ubuntu):
status:	New → In Progress
assignee:	nobody → dann frazier (dannf)

Ubuntu Foundations Team Bug Bot (crichton) on 2022-01-27

tags:

added: patch

Revision history for this message

Launchpad Janitor (janitor) wrote on 2022-01-31:

This bug was fixed in the package flash-kernel - 3.104ubuntu6

---------------
flash-kernel (3.104ubuntu6) jammy; urgency=medium

  * Introduce "Boot-Kernel-Max-Size" and support for compressing kernel
    images that exceed it. This will allow installation of larger
    uncompressed kernels on HP ProLiant m400 cartridges. LP: #1954692
  * Drop support for HP ProLiant m800 cartridges. The kernel flavor they
    require (-keystone) never shipped in Ubuntu.

-- dann frazier <email address hidden> Mon, 31 Jan 2022 16:47:18 +0000