Re: [Xen-devel] [PATCH] xen/arm: Fix rtds scheduler for arm

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 30/01/15 15:56, Andrew Cooper wrote:
> On 30/01/15 15:46, Julien Grall wrote:
>> Hello Denys,
>>
>> On 30/01/15 15:40, Denis Drozdov wrote:
>>> From: denys drozdov <denys.drozdov@xxxxxxxxxxxxxxx>
>>>
>>> Update RT scheduler to run on arm platform
>> You need to give more background of the problem (i.e why you have to
>> disable the IRQ on ARM).
>>
>> As the scheduler is common with x86, I would expect the problem is also
>> happening on this architecture.
> 
> Changing a spinlock_irq into an irqsave is safe, functionally speaking,
> but it is concerning that the scheduler appears to be called in
> different interrupt states between architectures.

For instance credit2 is also using vcpu_schedule_lock_irq... Although,
IIRC, it's not used by default. So it has to be fixed too on ARM.

In any case, the commit message needs more background such as stack
trace and/or explaining why we have to take spinlock_irq.

This may also need to document context_saved to explain the IRQs may not
be enabled when this function is called.

Regards,

-- 
Julien Grall

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