[libvirt] [PATCH v4 0/8] Add support for taking screenshots of domain console

[Daniel P. Berrange]

On Thu, May 12, 2011 at 06:29:07PM +0200, Michal Privoznik wrote:
> This series adds support for taking screenshots of a running domain console.
> The iohelper was added a new argument - delete file after transfer. This is
> needed, because the screenshot is written to file and asynchronously transferred
> to client.
> 
> New API is accessible via virsh screenshot <domain> <path> <screnID>;

Hmm, but we have two different ways of having multiple screens.

 - A single graphics card, with multiple virtual monitor outputs

    <video>
      <model type='vga' vram='9216' heads='4'/>
    </video>

  VirtualBox graphics card supports this

 - Multiple graphics cards, each with one monitor output

    <video>
      <model type='qxl' vram='9216' heads='1'/>
    </video>
    <video>
      <model type='qxl' vram='9216' heads='1'/>
    </video>
    <video>
      <model type='qxl' vram='9216' heads='1'/>
    </video>
    <video>
      <model type='qxl' vram='9216' heads='1'/>
    </video>

  QEMU supports this with QXL


It is perfectly possible to combine both, to have multiple graphics
cards each with multiple outputs.

So we need to define what we mean by 'screen' number. We could
have separate  'device' and 'head' parameters, or we have 'screen'
and declare that heads are enumerated, before devices.

So, eg with a config like

    <video>
      <model type='qxl' vram='9216' heads='2'/>
      <alias id='video0'/>
    </video>
    <video>
      <model type='qxl' vram='9216' heads='4'/>
      <alias id='video1'/>
    </video>

Then, screen is calculated as

  Screen  Device  Head
   0      video0  0
   1      video0  1
   2      video1  0
   3      video1  1
   4      video1  2
   5      video1  3



Incidentally an RFE is needed against QEMU, since it can only do screen
dump of the first device :-(

Daniel
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