On Tue, Sep 23, 2014 at 4:01 PM, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote: > On 23 September 2014 14:52, Christoffer Dall > <christoffer.dall@xxxxxxxxxx> wrote: >> If anyone feels like reviewing my patch and giving it a quick test on a >> BE system with a version of QEMU with the pl011 level-triggered patch, > > FWIW, any old version of QEMU running the vexpress-a15 model > will also use level-triggered interrupts for pl011, because > the upstream DTB which we use for that board has always > correctly marked the pl011 and all the other motherboard > devices as being level-triggered. > > I'm still not 100% convinced we shouldn't mark the > virtio-mmio devices as level-triggered, incidentally. > I *think* that (a) the spec pretty heavily implies that > the lines behave as level triggered but (b) the > specific text in the spec about required guest code > to avoid races (s.2.4.2 of the 0.9.5 spec) means that > even if the interrupt controller treats them as edge > triggered it's OK. > I think we should really sit down and figure out the right thing to do during KVM Forum if we can allocate a slot for that. Marc seems to also have some input he would like to share on this subject. For the record, I'm fine with changing the virtio-mmio devices, but it's probably worth quickly measuring the performance impact first. Thanks, -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
