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

[Marc-André Lureau]

Hi

On Fri, Jul 17, 2015 at 3:50 PM, Paolo Bonzini <address@hidden> wrote:
> The offset should be 0...

Yeah, except if we want to prepend other kind of data in the same
allocation, or we want to split somehow usage of this region. I think
it's more future-proof to have it if we introduce a new message.

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

For some reason, vhost_get_log_size() also takes pc-bios region. I
think it's quite unnecessary given that the backend will not have
access to this region. I can provide a simple fix for that I suppose.

get_log_size() also computes the size of the rings, I wonder if it's
necessary since the dev->mem->regions should already contain the
rings, isn't it?

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

That's possible, if we assume that existing backends won't leak the
passed fds (vapp does for ex), perhaps it needs a new flag (vhost-user
features flags are common with vhost, not sure we want to add that
here, but where else)

-- 
Marc-André Lureau