Re: [BUG] XEN domU crash when PV grub chainloads 32-bit domU grub

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-09-22 at 08:22 +0100, Andrew Cooper wrote:
> 
> The segment registers indicate that the domU is executing in ring1 which
> makes it a 32bit guest (also why 32bit words are used for the stack
> dump), but r10 through r14 have 64bit values in.

r10..r14 are not visible to 32-bit guests but it appears that this dumping
function in Xen doesn't check for that and omit printing them.

I suspect that if these were zeroed or poisoned upon domain creation you
would see those values unmodified here.

> It does appear to be an intermittent bug in 32bit grub-xen in the
> eventual domU, but I have no help to offer with respect to debugging
> grub-xen further.

Me neither. I did suggest to Andreas that he also took it to grub-devel.
I'll reply to the original with a full quote and copy that list.

Ian.