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From: Thomas Huth <thuth@redhat.com>
Subject: Re: [kvm-unit-tests PATCH] powerpc: Add SPRs migration test
Date: Tue, 19 Apr 2016 10:20:31 +0200
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On 14.04.2016 18:43, Greg Harmon wrote:
> On Thu, Apr 14, 2016 at 1:18 AM, Thomas Huth <thuth@redhat.com> wrote:
>> On 12.04.2016 23:32, Greg Harmon wrote:
>>> David Gibson <dgibson <at> redhat.com> writes:
>>>> On Mon, 11 Apr 2016 11:23:46 +0200
>>>> Thomas Huth <thuth <at> redhat.com> wrote:
>>>>> On 11.04.2016 03:55, David Gibson wrote:
>>>>>> On Fri,  8 Apr 2016 13:35:29 +0200
>>>>>> Thomas Huth <thuth <at> redhat.com> wrote:
>>>>>>
>>>>>>> This test can be used to check whether the SPR (special purpose
>>>>>>> registers) of the PowerPC CPU are migrated right. It first fills
>>>>>>> the various SPRs with some non-zero value, then reads the values
>>>>>>> back into a first array, then waits for a key (with the '-w' option)
>>>>>>> so that it is possible to migrate the VM, and finally reads the
>>>>>>> values from the SPRs back into another array and then compares it
>>>>>>> with the initial values.
>>>
>>> Hi,
>>> In order to make this test automated, what if we extend the test device to
>>> return a save/restore generation number? It can report that in a
>>> register,and then the test can spin, waiting for that value to increase.
>>
>> The test device only works on x86, as far as I know, so I'm afraid it's
>> not usable for this case here on PowerPC.
> 
> That's too bad that test device doesn't run on PowerPC.  I'll try to
> send a patch sometime to add this type of register to the test device.

By the way, for x86, there is already such a mechanism specified, see:

https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg05600.html

... seems like it has just not been merged yet.

 Thomas