On Mon, Dec 19, 2011 at 04:36:38PM +1030, Rusty Russell wrote: > On Sun, 18 Dec 2011 12:18:32 +0200, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > > On Fri, Dec 16, 2011 at 12:20:08PM +1030, Rusty Russell wrote: > > > Perhaps a new feature VIRTIO_F_UNSTABLE? Which (unlike other features) > > > appears and vanishes around config writes by either side? Kind of a > > > hack though... > > > > Not sure how this can work in such a setup: when would guest > > check this bit to avoid races? > > A separate registers also seems nicer than a flag. > > > > Some other possible design choices: > > - a flag to signal config accesses in progress by guest > > host would need to buffer changes and apply them in one go > > when flag is cleared > > - a register to make host get/set config in guest memory > > - use a control vq for all devices > > - seqlock-style generation count register(s)? > Has the advantage of > being a noop if things never change. The counter can be in guest memory, right? So we don't pay extra exits. > - continue to ignore it ;) Since you decided on a config layout redesign it seems a good time to fix architectural problems ... > And yes, it's a more general problem than virtio_pci... > > Cheers, > Rusty. -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
