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Re: [Xen-devel] PCI passthrough w/ shared IRQ in xen/master

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] PCI passthrough w/ shared IRQ in xen/master
From: Michael D Labriola <mlabriol@xxxxxxxx>
Date: Fri, 19 Feb 2010 11:26:11 -0500
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Mark Hurenkamp <mark.hurenkamp@xxxxxxxxx>
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Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote on 02/19/2010 11:24:28 AM:

> On 19/02/2010 16:15, "Mark Hurenkamp" <mark.hurenkamp@xxxxxxxxx> wrote:
> 
> > When you do passthrough the device which has a shared IRQ, the domU 
will
> > load the appropriate driver, but Xen refuses to assign the IRQ to the
> > domU.
> > In your case (and mine as well), the driver in domU is not aware that 
it
> > has no IRQ, and thus starts generating interupts which are then caught 
by
> > Dom0 as spurious interrupts, in my case even causing Dom0 to crash at
> > times.
> 
> Are you sure the domU doesn't get the interrupts as well? Correct 
behaviour
> in Xen will be to send the interrupt to both dom0 and domU - since Xen 
can't
> work out which of the two it properly belongs to (and it could be both).
> 
> I would suggest try commenting out the content of the function
> kernel/irq/spurious.c:note_interrupt(). That will stop dom0 from 
reacting to
> the 'spurious' irqs that it sees and ignore them instead. See if that 
works
> for you.

On it.  Let you know what happens.

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