Bug#776450: Xen PVH support for grub-xen in Buster

[Colin Watson]

On Mon, Jan 07, 2019 at 12:43:12AM +0100, Hans van Kranenburg wrote:
> So, if I go to my upstream build directory and follow the same recipe:
> 
> -$ mkdir -p grub_dir/boot/grub
> -$ sed -e "s/@@PVBOOT_ARCH@@/i386-xen_pvh/" <
> ~/path/to/debian/grub/packaging/debian/grub-xen-host_grub.cfg >
> grub_dir/grub.cfg
> -$ tar -cf - -C grub_dir grub.cfg > grub_memdisk
> -$ ./grub-mkimage -O i386-xen_pvh -c
> ~/build/grub/grub/debian/grub-xen-host_grub-bootstrap.cfg -d
> ./grub-core/ ./grub-core/*.mod -m grub_memdisk -o grub-i386-xen_pvh.bin
> 
> Now I scp this grub-i386-xen_pvh.bin to my Xen dom0 and use it in the
> guest config:
> 
> ---- >8 ----
> kernel = "/root/grub-i386-xen_pvh.bin"
> type = "pvh"
> ---- >8 ----
> 
> Now I start with xl create -c and voila, a blue grub menu, a countdown
> of 5 seconds and the whole thing starts correctly!

Excellent!  Thanks for the test.

> I've been looking at the modules in the domU and even had copied
> everything into /boot/grub/i386-xen_pvh manually, but it seems this is
> not used at all. It also works if I remove all of that again. So I'm
> still wondering what that's for.

The modules in the domU are used if you use the two-stage system, but
you aren't doing that at this point.  It's also possible for them to be
used in a less reliable way in the one-stage system if your grub.cfg
involves (explicitly or implicitly) loading modules that aren't in the
core image that was created by grub-mkimage.  There are certainly
possible setups that wouldn't use modules from the domU.

-- 
Colin Watson                                       [cjwatson at debian.org]