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

[Dr. David Alan Gilbert]

* David Gibson (address@hidden) wrote:
> 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.

I've added that text into the commit message.

Dave

> 
> -- 
> 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


--
Dr. David Alan Gilbert / address@hidden / Manchester, UK