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Re: [Xen-devel] Re: [PATCH] qemu vnc updates

To: Anthony Liguori <anthony@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] qemu vnc updates
From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Date: Tue, 26 Feb 2008 16:22:24 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
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On Tue, Feb 26, 2008 at 10:15:51AM -0600, Anthony Liguori wrote:
> Stefano Stabellini wrote:
> >Hi all,
> >reading qemu code I realized that the qemu vnc server sometimes sends 
> >framebuffer updates even if the client didn't request any.
> >This is not consistent with the RFB protocol spec and can break some 
> >clients.
> It's actually consistent with the RFB spec.  Have you seen any clients 
> break?
> The RFB spec states pretty clearly that a single 
> FramebufferUpdateRequest may generate 0 or more FramebufferUpdate 
> events.  Once a client has sent a single FramebufferUpdate request, it 
> should expect to continue to receive more FramebufferUpdates for an 
> indefinite period of time according to the specification.

The reverse is true too - the server may coallese multiple 
into a single FramebufferUpdate reply. There is no 1-to-1 mapping between
request & reply as this patch attempts to enforce.

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