Full Disclosure mailing list archives
Re: Xfree86 video buffering?
From: James Tucker <jftucker () gmail com>
Date: Fri, 25 Feb 2005 13:08:20 +0000
On Thu, 24 Feb 2005 23:26:36 -0500, Valdis.Kletnieks () vt edu <Valdis.Kletnieks () vt edu> wrote:
I don't think this is at all easily solvable - when the X server starts up, the card is probably in console mode using the VGA emulation, which is pretty brain-dead and doesn't touch much of the card memory (when you have 32M or 64M on-card, that 640x480 gets lonely sitting in the corner). The X server first has to pop it into the native NVidia/ATI/whatever graphics mode (remember, it has to do that *before* it can access the video memory - you can't get there while still in VGA emulation).
Is it not possible to switch processing modes without switching video modes? Could a fast(er) operation, such as a blank intermediate pallete be loaded to 'wash out' all coloured pixels on the screen?
Then it can proceed to clear out the on-card memory. Unfortunately, if the X server pauses in between setting the mode and clearing the memory, you get to see the uninitialized (and therefor left-over) buffers.
Damn busy waiting...
About the best you can do here is fix the server to try to not do any time-intensive operations between the mode set and the clear.
Isn't this a problem when it comes to POSIX compliance?
There's multiple reasons why it can even survive a power cycle. In my case, I've only been powering off for a few seconds (stupid laptop doesn't have a MNI Reset button, which would be quite helpful when doing kernel-level hacking), and the voltage levels in the RAM hadn't decayed all the way to bit lossage.
It's like my father always said, turn it off, count to thirty, now you can go again.. ;-) I knew the electronic engineers were keeping something from us... now what about that third 'bit'? _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- Re: Xfree86 video buffering?, (continued)
- Re: Xfree86 video buffering? KF (Lists) (Feb 23)
- Re: Xfree86 video buffering? Eric Paynter (Feb 24)
- Re: Xfree86 video buffering? Eric Windisch (Feb 24)
- Re: Xfree86 video buffering? Rodrigo Barbosa (Feb 24)
- Re: Xfree86 video buffering? KF (Lists) (Feb 24)
- Re: Xfree86 video buffering? Rodrigo Barbosa (Feb 24)
- Re: Xfree86 video buffering? Eric Windisch (Feb 24)
- Re: Xfree86 video buffering? KF (Lists) (Feb 24)
- Re: Xfree86 video buffering? Rodrigo Barbosa (Feb 24)
- Re: Xfree86 video buffering? Valdis . Kletnieks (Feb 24)
- RE: Xfree86 video buffering? Allan (Feb 25)
- Re: Xfree86 video buffering? James Tucker (Feb 25)
- Re: Xfree86 video buffering? Riad S. Wahby (Feb 25)
- Re: Xfree86 video buffering? bkfsec (Feb 25)
- Re: Xfree86 video buffering? Stan Bubrouski (Feb 25)
- Re: Xfree86 video buffering? bkfsec (Feb 25)
- Re: Xfree86 video buffering? Stan Bubrouski (Feb 25)