Jesse Barnes wrote:
> On Tuesday, June 24, 2008 3:46 am David Vrabel wrote:
>> PCI MSI interrupts are masked and unmasked using a method (by writing
>> the MSI Enable capability bit) that is prohibited by the PCI specification.
> 
> Yeah, it's probably quite a bit slower too (I assume you're talking about 
> io_apic_64's msi_mask_irq).  Seems like masking this at the ioapic level 
> would make more sense anyway...
> 
>> This behaviour can cause missed interrupts with some devices if the
>> interrupt is asserted by the hardware while MSI is disabled.
>>
>> I believe the interrupt should be masked/unmasked on the interrupt
>> controller (the APIC on x86, for example).   I'm going to test this now
>> and see if it works.

After further research it seems that MSI interrupts aren't routed via
the IO-APIC, so this cannot be done.

I think the only solution is to not perform any sort of masking and rely
on the device driver being able to handle this.

David
-- 
David Vrabel, Senior Software Engineer, Drivers
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