[Bug 1878541] Re: Grub fails to load kernel from squashfs if mem < 1500mb

[Dimitri John Ledkov]

The minimum reproducer i have is this:

1) Fetch UC20 image from http://cdimage.ubuntu.com/ubuntu-core/20/edge/pending/
2) boot to grub cmdline prompt
2) execute

loopback loop (hd0,gpt3)/pc-kernel_502.snap

(or use tabcompletion for the right kernel snap)

Equivalent command on UC18 image (with bionic's grub) result in no
additional memory used, with the same kernel snap.

On UC20 image, executing that command uses up 400MB of RAM which does
not appear to be reclaimed.

It appears to be irrelevant as to what underlying fs type is (UC18 had
kernel snap on ext4, UC20 has it on ESP/fat).


** Changed in: grub2 (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1878541

Title:
  Grub fails to load kernel from squashfs if mem < 1500mb

Status in snapd:
  New
Status in grub2 package in Ubuntu:
  Confirmed

Bug description:
  Booting a uc20 system fails early currently. The image used was:
  http://cdimage.ubuntu.com/ubuntu-core/20/beta/20200513.2/

  Attached is a screenshot of the debug output.

  This appears to be some sort of regression with grub in 20.04 or with
  UEFI grub - this used to work in uc18.

  Note that there is memory < 1500mb

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