Comment 20 for bug 1885662

Hi,
I've seen this fly bug by and wanted to warn (= ask for early testing) about an associated risk.
Changing rom sizes happens sometimes and back in the day of bug 1713490 it was unplanned :-/
This time we at least have the benefit of doing it consciously.

The tricky part is cross release / cross update live migration.
Your guest has memory of a given size allocated for that ROM and that is usually derived from the file size - when migrating to a target that has a different file size it will allocate a different size and fail the migration due to that.
And that is the reason why - usually - one is supposed to keep the size as-is and if changing it use an extra file for the new size. That might explain some of the cases you saw with other Distributors.

I wanted to ask to test the following migrations:
1. same release: pre-upgrade -> post-upgrade
2. same release: post-upgrade -> pre-upgrade (there is no hard guarantee for this, but we try rather hard to keep it working whenever possible)
3. cross release: bionic -> unupdated focal (just to verify your setup works)
4. cross release: bionic -> updated focal
5. cross release: unupdated focal -> jammy (just to verify your setup works)
6. cross release: updated focal -> jammy
7. cross release: bionic -> unupdated focal -> jammy (just to verify your setup works)
8. cross release: bionic -> updated focal -> jammy

Maybe we are lucky and the ram allocation for edk2 roms is smarter than the one for ipxe and this is not an issue. But I wanted to make you aware of the major regression risk and ask you to test this in advance.

#3, #5, #7 are self checks and should always work, but if either of #1, #4, #6, #8 and to some extent if #2 fails - this needs to go back at the drawing board and probably needs a bigger fix with the same design as bug 1713490.