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Date: Wed, 06 Jan 2010 20:59:37 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: [Qemu-devel] Re: Planning for 0.13
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Anthony Liguori <aliguori@linux.vnet.ibm.com>, qemu-devel@nongnu.org


>>> 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.

> 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