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Re: [Xen-devel] xen/arm: Query - vgic nr_spis value for domU

Hi Vijay,

On 24/02/15 10:49, Vijay Kilari wrote:
> On Tue, Feb 24, 2015 at 3:53 PM, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
>> On Tue, 2015-02-24 at 09:48 +0000, Julien Grall wrote:
>>> On 24/02/2015 09:41, Ian Campbell wrote:
>>>> domU should get configurable nr_lpi in the same way Julien has done for
>>>> spi. Unless it is possible to make nr_lpi dynamic based on the guests
>>>> actual usage patterns (i.e. alloc on demand), that would be ok too.
>>> You have to expose the number of LPI's used in GICD_TYPER.
>>> So unless we decide to use hardware value for the guest, we would have to
>>> set a static one at domain creation.
>> Right.
>> With alloc on demand it might be reasonable to expose a pretty high
>> number (like the h/w limit) in GICD_TYPER if the actual associated
>> resources aren't actually allocated until they are used.
> I propose to add radix tree for each domain for pending_lpis
> (synonymous to pending_irq for lpis)
> and allocate pending_lpi structure whenever irq_descriptor is 
> allocated/removed
> Destroy this radix tree when domain is destroyed.

I'm not sure what you mean by "allocating the pending_lpi whenever
irq_descriptor is allocated/removed"... The irq_desc and pending_lpi
should be allocated differently.

Anyway, I guess it will be easier to understand with your upcoming patch


Julien Grall

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