Re: [PATCH V2 00/11] Live update: cpr-exec

[Peter Xu <peterx@redhat.com>]

On Tue, Aug 06, 2024 at 04:56:18PM -0400, Steven Sistare wrote:
> > The flipside, however, is that localhost migration via 2 separate QEMU
> > processes has issues where both QEMUs want to be opening the very same
> > file, and only 1 of them can ever have them open.

I thought we used to have similar issue with block devices, but I assume
it's solved for years (and whoever owns it will take proper file lock,
IIRC, and QEMU migration should properly serialize the time window on who's
going to take the file lock).

Maybe this is about something else?

> 
> Indeed, and "files" includes unix domain sockets.  Network ports also conflict.
> cpr-exec avoids such problems, and is one of the advantages of the method that
> I forgot to promote.

I was thinking that's fine, as the host ports should be the backend of the
VM ports only anyway so they don't need to be identical on both sides?

IOW, my understanding is it's the guest IP/ports/... which should still be
stable across migrations, where the host ports can be different as long as
the host ports can forward guest port messages correctly?

Thanks,

-- 
Peter Xu