--- Linus Torvalds <[EMAIL PROTECTED]> wrote:
> 
> On Wed, 26 Feb 2003, Sven Luther wrote:
> > 
> > Yes, and you have to divide the fb memory in two, one for each
> head, or
> > something such, and each head will have its separate offscreen
> memory
> > manager, possibly using different screen strides.
> 
> Side note: I know that what people are mostly talking about is having
> two
> separate displays with different contents, but please, if you're
> thinking
> about this, try to make the solution generic enough that you can have
> two
> separate displays with the _same_ backing store content at different
> resolutions and different pointers.
> 
> Yeah, not all chips support this, but many do (and probably all that
> support multiview support this subset), and it's invaluable for
> having
> laptops that have small LCD's. In particular, it should be possible
> to
> have the pointer associated with the LCD, and scroll around on the
> LCD
> while the CRT output (ie usually a projector) shows the whole picture
> (obviously without scrolling or without any pointer).
> 
> Right now, as far as I can tell, XFree86 can not do this sanely. You
> can 
> have two separate X servers for the different outputs, or you can
> have the 
> exact _same_ output on both CRT controllers, but you can't make the
> two 
> displays look like "separate windows into the same area".
> 
> And it really sounds like the DRI dual-head is not that conceptually 
> different from this. The only issue is whether you share the frame
> buffer 
> or not.
> 
> So you have several cases:
>  - shared framebuffer, shared CRT control
>  - shared framebuffer, but separate CRT control (and "mouse focus" or
> 
>    whatnot)
>  - separate framebuffers, and separate CRT control (and "mouse
> focus")
> 
> Is this what you call "mirrored viewports"?
> 
>                       Linus
> 

I think we are all talking about the same thing.  What you described
above might be covered by the "zoomed" mode (you could zoom in or out),
which is kind of a subset of the mirrored mode.  In that case the
second crtc would be a viewport into the same framebuffer, only with a
different resolution.  I agree that Xfree doesn't really have a good
interface for this at the moment. it tends to be too entity specific.


Alex


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