Re: [Xen-devel] [PATCH] Bypass mask bit of msix entry in xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.03.13 at 11:50, Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx> wrote:
> On 2013-03-21 18:12, Jan Beulich wrote:
>> Furthermore, without explanation I also don't see how the mask
>> bit is now being dealt with properly: From an abstract pov you'd
>> need to merge ("or") the guest-requested mask bit state with what
>> Xen needs for its own purposes. I don't see anything like that here
>> or in the qemu side patch.
> Right, I didn't consider combine xen's masking with guest's.
> My patch just target making irq affinity in old hvm guest work and 
> sometimes no irq handler panic.
> But I would like to know what's the result if guest's mask setting 
> doesn't pass to device,
> interrupt loss or something else? I see current implemention didn't 
> passthrough mask bit too.

The effect of this is unknown, as it depends on the particular
driver behavior and assumptions. Loss of interrupts, however,
doesn't appear to be problematic here; instead, interrupts
getting delivered when the driver doesn't expect them seems
to be the much bigger problem.

Jan


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