Messages in this thread | | | Date | Wed, 5 Sep 2012 17:51:53 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH v9 1/2] kvm: Use a reserved IRQ source ID for irqfd |
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On Wed, Sep 05, 2012 at 05:35:43PM +0300, Avi Kivity wrote: > On 08/22/2012 03:41 AM, Michael S. Tsirkin wrote: > >> > >> I assumed you were pointing out the level vs edge interaction. If we > >> call that a userspace bug, I can just drop this. Thanks, > >> > >> Alex > > > > level is userspace bug I think :) > > I don't see how it's a bug. Suppose we have a vfio device that shares a > gsi with an emulated device. The emulated device naturally uses > KVM_IRQ_LINE (it has no need to re-sample on ADN), while vfio naturally > has to use irqfd.
Absolutely. But vfio needs to use irqfd with the new flag. Using existing irqfd for level is a bug.
> Note one would expect that each irqfd gets its own irq source id, since > they are all independent level sources. The reason they don't is that > we shut them down anyway and let the sources re-trigger (it is more > accurate to say that they have no irq source id, but that would just > muddle the implementation). > > Alex, if the conclusion is that we do need this patch, then please add a > comment explaining why we can share the source id among all irqfd users. > > -- > error compiling committee.c: too many arguments to function
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