Re: [Xen-devel] PCI MSI questions

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 24.07.08 09:20 >>>
>On 24/7/08 08:02, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
>> 1) There currently seems to be a hidden requirement of NR_PIRQS in the
>> kernel needing to be no smaller than NR_IRQS in the hypervisor.
>> Otherwise, the pirq returned from PHYSDEVOP_map_pirq may collide
>> with the dynamic IRQs in the kernel or even be out of range altogether.
>> Therefore I think that NR_PIRQS has to become a variable defaulting
>> to 256 but getting initialized from a hypervisor reported value (perhaps
>> in start_info, or else from a new (sub-)hypercall).
>
>Or have the kernel remap the return value of map_pirq into its own PIRQ
>namespace, and maintain appropriate translation info? Although, it'd be nice
>to have dynamic NR_IRQS sizing anyway -- people who want to run lots of
>domUs currently may have to recompile dom0 with more DYNIRQS.

So what route would you prefer to go (so that if I'm able to get to it I
wouldn't end up submitting a patch you'd have wanted done the other
way around)?

Jan


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