Re: [Xen-devel] Xen-unstable: Bisected Host boot failure on AMD Phenom

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/03/17 17:29, Sander Eikelenboom wrote:
> On 02/03/17 15:55, Andrew Cooper wrote:
>> On 02/03/17 14:42, Sander Eikelenboom wrote:
>>> Hi Andrew / Jan,
>>>
>>> While testing current xen-unstable staging i ran into my host rebooting in 
>>> early kernel boot. 
>>> Bisection has turned up:
>>>     5cecf60f439e828f4bc0d2a368ced9a73b130cb7 is the first bad commit
>>>     Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>     Date:   Fri Feb 17 17:10:50 2017 +0000
>>>
>>>     x86/cpuid: Handle leaf 0x1 in guest_cpuid()
>>>
>>> Hardware is a AMD phenom x6.
>>> Below is the output of serial console of a failed boot.
>> Hmm.  Sorry for breaking this (although my AMD servers are booting fine).
> No problem, it is the staging branch of the unstable tree anyway ;-)
>
>> It is unfortunately not entirely obvious what Linux is objecting to, and
>> must be related to something visible in the emulated view.
>>
>> Does this delta make any difference?
> Yes it does, boots fine with this patch applied, thanks !

That is bad though. :s

It means that something in dom0 has an aversion to my attempt to lie
less about the topology.

Do you mind checking whether

res->b = cpuid_ebx(0x1) & 0xff00ffffu;

causes is to break again?

That will confirm whether the breakage is to do with Logical Processors
Per Package (which I suspect is the case), or the APIC ID field (which
has always been unstable in the past).

~Andrew

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