Re: [Qemu-devel] [PATCH 2/2] Route IOAPIC interrupts via ISA bus

[Avi Kivity]

On 08/27/2009 10:35 AM, Gerd Hoffmann wrote:
> > > BTW: Seems linux doesn't use IRQ 5 even with lots of PCI devices,
> > > instead it makes them share 10+11 ...
> >
> > We could change the defaults to include 5, but maybe it makes more sense
> > to fix Linux to distribute active PCI IRQs across the resources it has
> > at its disposal.
>
> i.e. Linux decides to stick with the defaults (starred) here ...
>
> ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
> ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)
> ACPI: PCI Interrupt Link [LNKB] (IRQs 5 *10 11)
> ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)
> ACPI: PCI Interrupt Link [LNKD] (IRQs 5 10 *11)
>
> ... instead of trying to minimize IRQ sharing by using IRQ 5?

Yes.  And if it turns out you have two active devices and 6 inactive 
devices, move the two active devices to private lines and pile up the 
inactive ones on the leftover.

> > They'll be slow regardless. I should be easy to support msi on e1000
> > though.
>
> What is needed on the guest side?  Looks like even 2.6.30 doesn't use 
> MSI for virtio-net ...

virtio msi support was merged in 2.6.31.  For e1000, guest support is 
presumably there, just need to wire it into the device.

--
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