Re: multiboot2 and module2 boot issues via GRUB2

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 01/04/2021 09:44, Roger Pau Monné wrote:
> On Thu, Apr 01, 2021 at 09:31:07AM +0200, Jan Beulich wrote:
>> On 01.04.2021 03:06, Roman Shaposhnik wrote:
>>> And the obvious next question: is my EVE usecase esoteric enough that
>>> I should just go ahead and do a custom GRUB patch or is there a more
>>> general interest in this?
>> Not sure if it ought to be a grub patch - the issue could as well
>> be dealt with in Xen, by concatenating modules to form a monolithic
>> initrd.
> I would rather have it done in the loader than Xen, mostly because
> it's a Linux boot specific format, and hence I don't think Xen should
> have any knowledge about it.
>
> If it turns out to be impossible to implement on the loader side we
> should consider doing it in Xen, but that's not my first option.

Concatenating random things which may or may not be initrds is
absolutely not something Xen should do.  We don't have enough context to
do it safely/sensibly.

Honestly, I like the idea of supporting something like this generally in
grub.  Linux already commonly has initrd preparation prepending an
uncompressed microcode CPIO archive, and I can see a usability advantage
from maintaining the initrd fragments separately.

Looking at the grub manual, this behaviour of the `initrd` command isn't
even documented.  Perhaps that should be fixed first, and then maybe
`module2_multi` added too?

~Andrew