Re: Prevent IRQ sharing for PCI passthrough

[Avi Kivity <avi@redhat.com>]

On 05/14/2010 12:37 PM, Dirk Gouders wrote:
>    
>>> Even after extensive searching/reading, I am not sure if it possible to
>>> prevent a PCI card from sharing an interrupt with other devices or
>>> probably manually assign a free interrupt to that card via some kernel
>>> parameter and would be glad if someone could give me an answer to that
>>> question.
>>>
>>>        
>> There is an ACPI _SRS method which can be used to move interrupts
>> around.  However Linux doesn't appear to expose it.  Even if it did,
>> the interrupt may be shared on the motherboard, in which case nothing
>> would help (though you might be able to share it with unused devices).
>>      
> You mean by providing a custom DSDT, right?
> A quick look in drivers/acpi/pci_link.c shows a TBD comment mentioning
> _SRS but I will have to have a deeper look at this subject, because its
> quite new to me.
>
>    

No, there should be an _SRS method in your existing DSDT.  But Linux 
doesn't call it (except after resume etc.) and doesn't allow the user to 
use _SRS to move interrupts around.

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