Re: [Qemu-devel] [PATCH for-2.10 2/2] xilinx-spips: add a migration blocker when using mmio_execution

[Peter Maydell]

On 1 August 2017 at 10:41, Peter Maydell <address@hidden> wrote:
> On 1 August 2017 at 10:35, KONRAD Frederic <address@hidden> wrote:
>>
>>
>> On 08/01/2017 11:30 AM, Edgar E. Iglesias wrote:
>>> At this stage, perhaps we should just register the blocker when this dev
>>> realizes.
>>>
>>> If a request_ptr comes in during migration, the VM will fail either way...
>
>> Yes but this will breaks migration for the spips device everytime
>> and not only when mmio-execution is used?
>
> This line of thought is why I ended up suggesting just disabling
> the exec-in-place feature -- that way we just don't introduce
> what would be a new-in-2.10 feature, rather than breaking something
> that used to work in 2.9.

OK, so what's the plan here? We have several options:
 * just disable exec-from-spips for 2.10 (I sent a patch for that)
 * disable exec-from-spips for 2.10 but with a device x-property
   to allow the user to turn it on again if they really want it
 * this patch or variants on it which try to only disable
   migration if exec-from-spips is actually used by the guest
   (I don't like these because of the awkward corner cases if
   migration and the guest using exec-from-spips happen at the
   same time)

So my current view remains "we should just disable this feature
for 2.10 and we can implement it properly with handling of
migration for 2.11", unless somebody cares enough to implement
the x-property thing within the next day or so.

thanks
-- PMM