On Wed, 6 Nov 2024 at 21:30, Peter Xu <pet...@redhat.com> wrote: > IIUC we can't simply change it to this. We can do this with a compat > property and we can start sending a magic in the preempt channel, but then > the code still needs to keep working with old binaries of QEMU, so in all > cases we'll need to keep the old complexity for quite a while.
* I see...sigh. > Handshake, in my mind, will use a totally separate path, then the hope is > we'll move to that with more machine types and finally obsolete / remove > this path. * I need to check how 'separate path' works. > But note again that I still think your goal of enabling multifd + postcopy > may not require that new flag yet, simply because after 7.2 qemu will > connect preempt channel later than the main channel. I think logically > QEMU can identify which channel is which: the preempt channel must be > established in this case after both main thread and multifd threads. * You mean, instead of relying on magic bytes, we check if both 'main channel' and 'multifd channels' already exist, then the incoming connection is assumed to be for the 'postcopy preempt' channel? Thank you. --- - Prasad
