Hi, > However, as part of this feature (explicit flush), I'd like to make the Guest wait until > the current resource (as specified by resource_flush or set_scanout) is flushed or > synchronized. But for a different feature I am thinking of (explicit sync), I'd like to > make the Guest wait for the previous buffer/resource submitted (available via > old_state->fb). For page-flipping I guess? i.e. you want submit a new framebuffer, then wait until the host doesn't need the previous one? That is likewise linked to a command, although it is set_scanout this time. So, right now qemu simply queues the request and completes the command when a guest sends a resource_flush our set_scanout command. You want be notified when the host is actually done processing the request. I still think it makes sense extend the resource_flush and set_scanout commands for that, for example by adding a flag for the flags field in the request header. That way it is clear what exactly you are waiting for. You can also attach a fence to the request which you can later wait on. take care, Gerd
