Re: [Xen-devel] [PATCH] Change spec of callback IRQ forPV-on-HVMonIA64

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 21/11/06 10:56, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:

>> OK, I now understand. Other OS tells xen GSI number as callback_irq,
>> and then xen look up virtual interrupt controller to find appropriate
>> vector by GSI number. This is the way to go. :-)
>> 
>> Thanks a lot,
>> Kevin
>> 
> 
> Keir mentioned in another thread that he will change qemu to support
> more GSIs (>16) soon, and this will become an issue with your patch
> since you're only looking at isa_irq_to_vector. Is there any common
> approach exported by linux kernel to find vector->GSI mapping in
> driver? If not, maybe an alternative is to provide a callback_irq_type
> which indicates whether the value is a GSI or vector?

We plan to add a callback_vector type to the Xen interface for x86 HVM, as
we will deliver event-channel notifications via an MSI-style poke directly
into the IRR of the appropriate local APIC. We'll continue to support
callback_irq type for compatibility.

 -- Keir


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