LCA: Updates on the X Window System [LWN.net]

LCA: Updates on the X Window System

Posted Jan 26, 2007 17:07 UTC (Fri) by pimlott (guest, #1535)
In reply to: LCA: Updates on the X Window System by bronson
Parent article: LCA: Updates on the X Window System

The obvious follow-up: Why isn't it fast? If video modes are set in the kernel (as seems the plan), in the common case where the mode is the same in the old and new virtual terminals, no reset should be necessary. But I'm a graphics ignoramus, so I may be missing something.

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LCA: Updates on the X Window System

Posted Jan 26, 2007 18:46 UTC (Fri) by bronson (subscriber, #4806) [Link]

When video modes are set in the kernel, it will be as you say.

Until then, it is up to the process to set up the card. How can the news process know what mode the card is currently in? Even if it COULD reliably read back the mode settings (and on most hardware you can't), it would also have to see if the framebuffer is obscured by a video surface or GL surface, or if it's rotated 90 degrees, or... It amounts to a ton of code.

So, until it's all in the kernel (2 years at least, maybe more, IMo) it's safest just to reset and start from scratch.