Re: Xen 4.5 random freeze question

[Julien Grall <julien.grall@linaro.org>]

On 11/19/2014 12:17 PM, Stefano Stabellini wrote:
> On Wed, 19 Nov 2014, Ian Campbell wrote:
>> On Wed, 2014-11-19 at 11:42 +0000, Stefano Stabellini wrote:
>>> So it looks like there is not actually anything wrong, is just that you
>>> have too much inflight irqs? It should cause problems because in that
>>> case GICH_HCR_UIE should be set and you should get a maintenance
>>> interrupt when LRs become available (actually when "none, or only one,
>>> of the List register entries is marked as a valid interrupt").
>>>
>>> Maybe GICH_HCR_UIE is the one that doesn't work properly.
>>
>> How much testing did this aspect get when the no-maint-irq series
>> originally went in? Did you manage to find a workload which filled all
>> the LRs or try artificially limiting the number of LRs somehow in order
>> to provoke it?
>>
>> I ask because my intuition is that this won't happen very much, meaning
>> those code paths may not be as well tested...
> 
> I did test it by artificially limiting the number of LRs to 1.
> However there have been many iterations of that series and I didn't run
> this test at every iteration.

am I the only to think this may not be related to this bug? All the LRs
are full with IRQ of the same priority. So it's valid.

As gic_restore_pending_irqs is called every time that we return to the
guest. It could be anything else.

It would be interesting to see why we are trapping all the time in Xen.

Regards,

-- 
Julien Grall