Bug#995397: Dropped support for 32-bit Xen PV guests should be mentioned in i386 release notes

[Andy Smith <andy@strugglers.net>]

Package: release-notes

As of Linux kernel version 5.9, support for 32-bit Xen guests
running in PV mode was dropped:

    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a13f2ef168cb2a033a284eb841bcc481ffbc90cf

Since bullseye comes with a 5.10 kernel, a 32-bit Xen PV guest may
be running fine under buster, do a dist-upgrade to bullseye which
completes without issue and then on reboot the kernel can't be
booted.

This has just happened to two of my customers, once last night and
once this morning, despite many years of us advising customers to
switch to 64-bit and/or PVH mode.

These 32-bit Xen guests can continue to run as 32-bit if they are
run as PVH mode guests instead, or they can continue to run as
64-bit PV mode guests (with 32-bit userland) if the guest admin
installs the amd64 kernel as per:

    https://wiki.debian.org/CrossGrading

I think this issue should be mentioned in the i386 release notes in
the upgrading from buster part. I am happy to propose some text for
that if it is agreed.

Thanks,
Andy