Re: [Qemu-devel] [PATCH v4 1/1] vhost user: add support of live migration

[Paolo Bonzini]

On 17/07/2015 02:19, Marc-André Lureau wrote:
>>> >> How does vhost-user do this?  I can see this patch providing enough
>>> >> support for *non*live migration.  However, it cannot be enough for live
>>> >> migration unless I'm missing something obvious.
>>> >>
>>> >> Paolo
>> >
>> > Agree. vhost-user should mmap the log memory and mark dirty pages when send
>> > or receive packets.
> This is already supported by vhost-user protocol, isn't it? The
> LOG_BASE/FD and vring log_guest_addr are provided. I can't find any
> vhost-user backend implementing dirty bitmaps yet though, but it looks
> like it should work. I suppose the backend should stop all IO after
> RESET_OWNER is received.

But LOG_BASE makes little sense across processes, and LOG_FD is unused
in QEMU, isn't it?  So this patch is not enough to add support of live
migration.

Paolo