Re: [Qemu-devel] [PATCH v4 12/47] Handle bi-directional communication for fd migration

[David Gibson]

On Mon, Nov 03, 2014 at 03:53:03PM +0200, Cristian Klein wrote:
> On 03 Nov 2014, at 5:12 , David Gibson <address@hidden> wrote:
> 
> > On Fri, Oct 03, 2014 at 06:47:18PM +0100, Dr. David Alan Gilbert (git) 
> > wrote:
> >> From: Cristian Klein <address@hidden>
> > 
> > This patch really, really requires a rationale in the commit message.
> > The reason it's necessary is certainly not obvious.
> 
> “”"
> libvirt prefers opening the TCP connection itself, for two reasons. First, 
> connection failed errors can be detected easier, without having to parse 
> qemu’s error output. Second, libvirt might be asked to secure the transfer by 
> tunnelling the communication through an TLS layer. Therefore, libvirt opens 
> the TCP connection itself and passes an FD to qemu using QMP and a 
> POSIX-specific mechanism. Hence, in order to make the reverse-path work in 
> such cases, qemu needs to distinguish if the transmitted FD is a socket 
> (reverse-path available) or not (reverse-path might not be available) and use 
> the corresponding abstraction.
> “”"
> 
> If the above message is clarifies the purpose of this commit, feel
> free to add it in the next version of the patch.

That would help, yes.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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