[SDL] (ATTN Sam Lantinga) Select Xinerama-screen?

Per Wigren wigren at home.se
Wed Sep 25 17:20:01 PDT 2002

On Monday, September 9, 2002, at 03:56 PM, Arne wrote:

>> My suspicion is that in 10.2, the backbuffer is transferred to the  
>> screen via busmaster DMA, but that operation is asynchronous and  
>> doesn't block - hence you can draw into the window buffer again  
>> before the DMA transfer is complete. If this is a case, putting a  
>> small SDL_Delay() call after SDL_Flip() (for the time being) will  
>> give the graphics hardware time to play catch up.
> Maybe this is an Quartz extreme sideeffect?

I've seen the same effect with QE disabled, so I find this unlikely.  
More likely is that 10.2 has added DMA support for the gfx hardware.

> Could be a problem while passing the window to OpenGl (that's what  
> they are doing as I've heard).

We don't actually pass the window to OpenGL - QE is completely  
transparent to SDL. But there may be some required locking/unlocking of  
the window buffer now that dma is used.

> Anyone tried to disable Quartz extreme, yet? (I dunno how, but maybe  
> this fixes the problem).

As root, edit  

Change IOAGPDevice to IOPCIDevice to enable/disable. You'll have to  
logout for the change to take effect.


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