ShadowFB + Composite + RandR + ?

[Thomas Winischhofer]

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Thomas Winischhofer wrote:
> Keith Packard wrote:
> 
>>>On Tue, 2005-09-27 at 22:00 +0200, Thomas Winischhofer wrote:
>>>
>>>
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>>>>Sorry for this monologue:
>>>>
>>>>Thomas Winischhofer wrote:
>>>>
>>>>
>>>>>PaintWindow and CopyArea and others (noticed especially PolyFillRect)
>>>>>are called even in case the composite manager has redirected a window.
>>>>
>>>>This assumtion was correct: My wrapped functions were called even for
>>>>off-screen drawables. I have added a check if the drawable is the
>>>>frontbuffer now and this works like a charm. No illegal boxes any more.
>>>
>>>
>>>So do you believe there is a bug in the composite code, a misfeature of
>>>that code which drivers should work around, or a bug in your driver?
> 
> 
> Well, it is no bug in composite, I would say. It is a problem with
> composite in combination with shadowfb.
> 
> Composite does it job as it should: It renders stuff into offscreen memory.
> 
> I needed shadowfb as a "shadow *front* buffer", not "framebuffer" in
> general, since I only rotate the front buffer. That's what shadowfb
> obviously isn't meant to be.
> 
> And as I just found out, if I enable the shadowfb option (everything
> else disabled, including 2D acceleration), X will crash as soon as the
> composite manager is started. This should be easy to reproduce for
> everybody, with any driver that supports shadowfb. And it will
> especially affect the sisusb driver as it depends on shadowfb.


... and strangely, it does NOT crash. The boxes seem all valid. And it
is even pretty fast with transparency enabled. Quite usable.

I think there is still something about this matter that I don't entirely
understand...

Thomas

- --
Thomas Winischhofer
Vienna/Austria
thomas AT winischhofer DOT net          http://www.winischhofer.net/

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