On Wed, 2019-09-11 at 20:15 +0100, Dr. David Alan Gilbert wrote: > > Extend the protocol slightly, so that a message can be used for kick > > and call instead, if VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS is > > negotiated. This in itself doesn't guarantee synchronisation, but both > > sides can also negotiate VHOST_USER_PROTOCOL_F_REPLY_ACK and thus get > > a reply to this message by setting the need_reply flag, and ensure > > synchronisation this way. > > I'm confused; if you've already got REPLY_ACK, why do we need anything > else? We already require the reply on set_mem_table as part of > postcopy.
Hmm? How's this related to set_mem_table? For simulation purposes, I need the kick and call (and error perhaps though it's not really used by anyone now it seems) to be synchronous messages instead of asynchronous event FD pushes. But I think enough words have been expended on explaining it already, if I may kindly ask you to read the discussions with Stefan and Michael here: https://lore.kernel.org/qemu-devel/20190902121233.13382-1-johan...@sipsolutions.net/ Thanks, johannes