Re: [Xen-devel] Bug#759018: [PATCH RFC] Provide prebuilt grub-xen binaries for host (dom0) use

[Colin Watson <cjwatson@xxxxxxxxxx>]

On Sun, Aug 24, 2014 at 10:42:37PM +0100, Ian Campbell wrote:
> The net result of the above is that the dom0 core.img built by the
> package will search /boot/grub/{i386,x86_64}-xen/core.elf (for the arch
> matching itself only) and then the version without the /boot prefix (for
> systems with separate /boot).
> 
> Colin mentioned at debconf that it would be good if these paths were
> standard across all distros -- probably this is best treated as
> something which upstream Xen specifies a standard on, so CCing xen-devel
> and Ian J who has previously been involved with these conversations. I'm
> not sure what the best way to promulgate the spec is -- I think a patch
> to add xen.git/docs/misc/pvgrub2.markdown would be sufficient (it would
> end up under http://xenbits.xen.org/docs/).

That was I think roughly what Ian J suggested late last year.

> Other alternatives for the paths might be things in the /boot/xen
> "namespace" rather than /boot/grub, I don't mind which so long as it is
> decided. Unless someone has a strong preference I'm inclined to go with
> the paths as they happen to be in the patch above.

My preference would be to have it be under /boot/xen/, if you're OK with
that.  The rationale is that some distributions configure GRUB with
"--program-transform-name=s/grub/grub2/", resulting in /boot/grub2/, and
I think life will be better if dom0 code doesn't have to deal with that.

As for the basename, "core.elf" is probably a bit generic if it's under
/boot/xen/.  We just need something vaguely sensible there, though, and
then the Debian grub-xen package and equivalents in other distributions
can create it.

There is also the question of whether the guest-side name should mention
GRUB.  One might argue that it shouldn't because all that matters is
that it uses the Multiboot protocol.  Then there is the question of who
gets to own the architecture names ...

As a strawman, how about:

  /boot/xen/pvboot-$arch.elf

... where $arch is the first bit of a GNU config triplet, modified such
that we always use i386 for that family?

-- 
Colin Watson                                       [cjwatson@xxxxxxxxxx]

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