On 27 August 2015 at 05:50, Jason Wang <jasow...@redhat.com> wrote: > On 08/26/2015 10:51 PM, Greg Kurz wrote: >> On Wed, 26 Aug 2015 15:21:59 +0100 >> Peter Maydell <peter.mayd...@linaro.org> wrote: >>> This seems to me like a bug in the caller. Why would anything >>> try to call into the memory subsystem to do a zero-size >>> transaction?
>> Here's the patch which needs zero-size eventfd: >> >> http://patchwork.ozlabs.org/patch/509428/ > Yes, this is because we want to use wildcard mmio eventfd (which > requires size to be zero) to speed up virtio 1.0 mmio. But *why* does it require the size to be zero? I still think the caller should just avoid trying to do zero-size memory operations: they don't make sense. What is a zero size operation supposed to mean? -- PMM
