* Maxime Coquelin (maxime.coque...@redhat.com) wrote: > > > On 06/28/2017 09:00 PM, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert"<dgilb...@redhat.com> > > > > **HACK - better solution needed ** > > We have the situation where: > > > > qemu bridge > > > > send set_mem_table > > map memory > > a) mark area with UFD > > send reply with map addresses > > b) start using > > c) receive reply > > > > As soon as (a) happens qemu might start seeing faults > > from memory accesses (but doesn't until b); but it can't > > process those faults until (c) when it's received the > > mmap addresses. > > > > Make the fault handler spin until it gets the reply in (c). > > > > At the very least this needs some proper locks, but preferably > > we need to split the message. > > Yes, maybe the slave channel could be used to send the ufds with > a dedicated request? The backend would set the reply-ack flag, so that > it starts accessing the guest memory only when Qemu is ready to handle > faults.
Yes, that would make life a lot easier. > Note that the slave channel support has not been implemented in Qemu's > libvhost-user yet, but this is something I can do if we feel the need. Can you tell me a bit about how the slave channel works? Dave > Maxime -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
