Bug#940628: grub-efi-{non-i386/amd64}-bin: Missing multiboot.mod

[Elliott Mitchell]

On Wed, Sep 18, 2019 at 07:06:49AM +0100, Colin Watson wrote:
> On Tue, Sep 17, 2019 at 04:29:37PM -0700, Elliott Mitchell wrote:
> > This makes it impossible for GRUB to load Xen on any platform that is not
> > either i386 or amd64.  Xen has support for running on ARM platforms, but
> > with no bootloader...
> > 
> > For example there is known to be working UEFI third-stage firmware for
> > the Raspberry PI:
> > https://github.com/tianocore/edk2-platforms/tree/master/Platform/RaspberryPi/RPi3
> > 
> > The absence of /usr/lib/grub/arm64-efi/multiboot.mod means entries
> > generated by /etc/grub.d/20_linux_xen cannot work.
> 
> I don't understand this point.  20_linux_xen looks like this:
> 
>     if ($grub_file --is-arm64-efi $current_xen); then
>         xen_loader="xen_hypervisor"
>         module_loader="xen_module"
>     else
>         if ($grub_file --is-x86-multiboot2 $current_xen); then
>             xen_loader="multiboot2"
>             module_loader="module2"
>         else
>             xen_loader="multiboot"
>             module_loader="module"
>         fi
>     fi
> 
> So on ARM (64-bit, anyway) it should use xen_hypervisor, not multiboot.

Okay, this may not be an issue for 2.04-3, and instead merely a problem
with 2.02+dfsg1-20.  On 2.02+dfsg1-20, 20_linux_xen is missing the first
if, which means it tries to load multiboot.mod which doesn't exist.

For 2.02+dfsg1-20 and 2.04-3 though I note there is a
/usr/lib/grub/arm64-efi/xen_boot.mod, but no
/usr/lib/grub/arm64-efi/xen_hypervisor.mod.  I don't know too much about
GRUB's workings, but I'm suspicious of 'xen_loader="xen_hypervisor"'.


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