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

[Paolo Bonzini]

On 17/07/2015 15:35, Marc-André Lureau wrote:
>> > LOG_FD is implemented in the kernel drivers/vhost/vhost.c.  It seems to
>> > be an eventfd-like mechanism to save on dirty bitmap scans.  However,
>> > it's not well documented how to implement it in a correct way.
> and it's not used by qemu, so hard to say if it actually work well.
> 
> > In any case, live migration needs a new message type (like LOG_MMAP_FD)
> > in the vhost-user protocol.
>
> Yes, perhaps with size and offset. I am looking at this.

The offset should be 0...

Do you know the size of the ram_addr_t space from
VHOST_USER_SET_MEM_TABLE's user address and size fields?

If the size isn't needed, you can reuse LOG_BASE, ignoring the content
of the payload and adding the SCM_RIGHTS file descriptor.

Paolo