Re: [Qemu-devel] [PATCH] qemu: msi irq allocation api

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, May 20, 2009 at 09:38:58PM +0300, Blue Swirl wrote:
> On 5/20/09, Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Wed, May 20, 2009 at 08:44:31PM +0300, Blue Swirl wrote:
> >  > On 5/20/09, Michael S. Tsirkin <mst@redhat.com> wrote:
> >  > > On Wed, May 20, 2009 at 08:21:01PM +0300, Blue Swirl wrote:
> >  > >  > On 5/20/09, Michael S. Tsirkin <mst@redhat.com> wrote:
> >  > >  > > define api for allocating/setting up msi-x irqs, and for updating them
> >  > >  > >  with msi-x vector information, supply implementation in ioapic. Please
> >  > >  > >  comment on this API: I intend to port my msi-x patch to work on top of
> >  > >  > >  it.
> >  > >  > >
> >  > >  > >  Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> >  > >  >
> >  > >  > Sparc64 also uses packets ("mondos", not implemented yet) for
> >  > >  > interrupt vector data, there the packet size is 8 * 64 bits.
> >  > >  > I think we should aim for a more generic API that covers this case also.
> >  > >
> >  > >
> >  > > Are you sure this is a good idea? MSI is tied to PCI, and PCI only has
> >  > >  MSI, not "mondos". What code would benefit from this abstraction?
> >  >
> >  > Sparc64 emulation, of course. I think also the API would be neater.
> >
> >
> > Since "mondos" are not interrupts, why use irqs for them?
> 
> I just said above that they are used for interrupt vector data. What
> makes you think they are not interrupts?

I'm sorry, I don't really know anything about sparc.
All I am saying is that in PCI, interrupts never pass data,
so qemu_set_irq as it is now, is a good API to send them.

For the sparc feature you describe, you probably want to add
a message data parameter to qemu_set_irq, but it's not
really useful for MSI.

-- 
MST