intel i915 hardware limit @ 2048x2048 for DRI?

[Keith Packard]

On Tue, 2007-06-12 at 11:15 +0200, Remy Bosch wrote:

> The hardware is the bottleneck in this respect?

Yes, the 3D engine has an 11 bit coordinate space at one point making it
impossible to draw to areas beyond 2048x2048. At another point, it has a
stride limit of 8192 bytes, so you can't even draw to a subset of a
larger frame buffer.

One more bit in both of these registers would have solved the problem
for pretty much any supportable monitor configuration (the chip can only
support two single-channel DVI outputs at the most; 1920 is the widest
size supported at single-channel speeds).

> And the driver might get around this in the future?

For multiple monitors, the driver could allocate multiple frame buffers
and step through them one at a time with appropriate clipping. It would
be icky, but could be made to work.

Of course, the latest hardware (965G/965GM) has plenty of coordinate
space, which does tend to reduce the odds that someone will get excited
enough to go fix the driver for older chips.

-- 
keith.packard at intel.com
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