Re: [Qemu-devel] [PATCH 1/2] pci: Add pci_device_get_host_irq

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-05-21 14:34, Michael S. Tsirkin wrote:
> On Mon, May 21, 2012 at 10:13:47AM -0300, Jan Kiszka wrote:
>> Add a PCI IRQ path discovery function that walks from a given device to
>> the host bridge, returning the IRQ number that is reported to the
>> attached interrupt controller. For this purpose, another PCI bridge
>> callback function is introduced: map_host_irq. It is so far only
>> implemented by the PIIX3, other host bridges can be added later on as
>> required.
>>
>> Will be used for KVM PCI device assignment.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> 
> interrupt injection is data path even for emulated devices.
> So instead of special casing device assignment I would like to see all
> devices converted to an API that caches irqs.
> 
> This will likely mean that we can maintain the final
> irq as part of the pci device structure, and
> this api will simply return it.

Yep, I definitely agree. It's just that such a design has to please even
more users than PCI devices, thus will likely take longer to settle than
the device assignment effort. Therefore I decided to rush forward with
an intermediate approach first.

Jan

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