[Qemu-devel] Re: Planning for 0.13

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 06, 2010 at 08:59:37PM +0100, Paolo Bonzini wrote:
>
>>>> We have ones that require read/write, ones that require send/recv, and
>>>> ones that require vhost interaction.  Really, the first two are the same
>>>> but the distinction is necessary for Windows.
>>>
>>> Not necessarily, you can open sockets on Windows so that they support
>>> read/write.  Just create it with
>>>
>>>    fh = WSASocket (domain, type, protocol, NULL, 0, 0);
>>>
>>> instead of socket.  Since Windows already has enough problems passing
>>> file descriptors to processes, imposing the above on an external
>>> management interface is not a huge chore.
>>>
>>> Paolo
>>
>> For linux read/write often isn't a good idea :)
>
> Yeah, only for "normal" raw sockets.

You mean TCP? We really need a UDP option BTW, and that
also needs special handling.

>> E.g. for packet sockets you really need to use sendmsg and set msg_name
>> with the proper protocol.  You also must use recvmsg and set MSG_TRUNC
>> otherwise packets can get truncatred silently.
>
> The situation for packet sockets is more similar to vnet headers no  
> (just learning all this stuff)?  They require code in qemu anyway, so  
> the helper would do only the set up/tear down.
>
> Paolo

Yes. And in that case, it does not make sense to force helper usage
where option to call 'socket' is just as easy.

-- 
MST