Re: [kvm-devel] [RFC] Deferred interrupt handling.

[Avi Kivity <avi@qumranet.com>]

Alan Cox wrote:
>> IMO the only reasonable solution is to disallow interrupt forwarding
>> with shared irqs.  If someone later comes up with a bright idea, we can
>>     
>
> Which means you are back to ISA bus devices. Even checking if an IRQ is
> currently unshared isn't simple as with hotplug this may change.
>
>   

Hotplug is user-controllable, so if the user refrains from adding pci
devices after assigning a device to the guest, it should work.  I think
that USB interrupts are assigned to the controller, not the device, so
USB hotplug can be ruled out.

I admit this is fairly weak.

>> implement it.  Otherwise the problem will solve itself with hardware
>> moving to msi.
>>     
>
> Only if MSI ever works properly on the bridges and hardware 8(
>   

Oh, I've no doubt it will be made to work -- there's money to be saved
in those irq lines.  And msi makes sense technically as well.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.