Re: [Xen-devel] [Xen-users] XEN bug at traps.c:3271

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.01.14 at 11:15, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Sun, 2014-01-19 at 13:37 +0100, Martin Unzner wrote:
>> Hi list,
>> 
>> I just installed Xen 4.3.1 for EFI according to 
>> https://bbs.archlinux.org/viewtopic.php?pid=1359933 and tried to boot 
>> it. There was a crash at the very beginning, notifying me of a bug at 
>> traps.c:3271. I could not find any logs, so I just noted the stack trace 
>> on a sheet of paper:
>> 
>> do_device_not_available
>> handle_exception
>> efi_get_time
>> get_cmos_time
>> init_xen_time
>> __start_xen
>> 
>> Does that mean my hardware is incompatible?
> 
> No, just that you've found a bug I think.
> 
> I'm copying the devel list here to see if anyone has any clues.

We've seen that before: You unfortunately have got one of those
UEFI implementations that utilize XMM (or, unlikely, FPU) registers,
and Xen doesn't allow this. Which is a consequence of the UEFI
specification being imprecise here: Some firmware implementors
read it to allow such, while my reading of it results in this not being
allowed. This is currently being brought up with the USWG for a
resolution. I'm afraid there's nothing you can do to work around
this for the time being (short of not booting via xen.efi, which -
depending on how you do it and depending on your firmware -
may have other bad side effects).

Jan


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