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Date: Thu, 20 Nov 2008 19:02:26 +0000
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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Subject: Re: [Qemu-devel] [PATCH 1 of 2] [UPDATE] DisplayState interface change
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To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel@nongnu.org

Paul Brook wrote:

> On Thursday 20 November 2008, Stefano Stabellini wrote:
>> Paul Brook wrote:
>>> No, I mean what happens when I have (for example) two emulated VGA
>>> devices, one displaying to SDL and the other to VNC? Or I want an
>>> intermediate later that composites multiple device outputs into a single
>>> host image.
>> If you want multiple device output you need multiple DisplayStates.
>> You need a DisplayState for each device output you want at the same time.
>> My patches do not make any harder to implement this scenario, actually
>> being the interface simpler it should be much simpler to handle this
>> case as well.
> 
> Maybe. We already have a per-display structure (QEMUConsole). IIUC you're 
> using DisplayState (which IMHO should be per host side display) to store per 
> device information.
> 

The assumption I made in my patches is the following:
DisplayState is the interface between multiple backend (for example vga
and serial, each of them has its own QEMUConsole) and multiple host-side
display (vnc.c and sdl.c).

If you want to see different things at the same time on multiple display
you need multiple DisplayState.
Then you can have, for example, two vga, each of them connected to an
sdl windows and a vnc server (2 windows and 2 servers total).