On Tue, Sep 19, 2023 at 04:18:57PM +0200, Matias Ezequiel Vara Larsen wrote: > On Tue, Sep 19, 2023 at 05:43:56AM -0400, Michael S. Tsirkin wrote: > > On Wed, Sep 13, 2023 at 05:04:24PM +0200, Matias Ezequiel Vara Larsen wrote: > > > Hello, > > > > > > This email is to report a behavior of the Linux virtio-sound driver that > > > looks like it is not conforming to the VirtIO specification. The kernel > > > driver is moving buffers from the used ring to the available ring > > > without knowing if the content has been updated from the user. If the > > > device picks up buffers from the available ring just after it is > > > notified, it happens that the content is old. > > > > Then, what happens, exactly? Do things still work? > > We are currently developing a vhost-user backend for virtio-sound and > what happens is that if the backend implementation decides to copy the > content of a buffer from a request that just arrived to the available > ring, it gets the old content thus reproducing some sections two times. > For example, we observe that when issuing `aplay FrontLeft.wav`, we hear > `Front, front left...`. To fix this issue, our current implementation > delays reading from guest memory just until the audio engine requires. > However, the first implementation shall also work since it is conforming > to the specification. > > Matias Sounds like it. How hard is it to change the behaviour though? Does it involve changing userspace? Maybe we need to fix the spec after all... -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
