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Re: [Xen-devel] [RFC PATCH v2 13/22] xen/arm: its: Add virtual ITS command support

On Thu, Apr 30, 2015 at 7:59 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> Hi,
> On 30/04/15 14:47, Stefano Stabellini wrote:
>>>>> If the devid is not within this range, the ITS won't recognize the value 
>>>>> and
>>>>> won't be able to send the interrupt.
>>>>> So this is clearly not the right value.
>>>> Sure, in that case the maximum value allowed by GITS_TYPER.Devbits.
>>>> Vijay, what is the value of GITS_TYPER.Devbits on your platform?
>>> It is 21 bits
>> I would imagine that 21 bits would be plenty to find an unused devid.
>> Alternatively we could use an inexistent function of a real device, such
>> as 00:00.1 (function 1 of the host bridge).
> As discussed IRL, this idea sounds good to me.
> Although I would be happy with any other way which ensure the devid is free.

Has prototyped with 00.00.1 as device id. But I see that Dom0 boot is
slow compared to polling mode. This could be because Dom0 has to keep
trapping on creader to check if creader is updated or not.


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