Full Disclosure mailing list archives
Re: Xfree86 video buffering?
From: bkfsec <bkfsec () sdf lonestar org>
Date: Fri, 25 Feb 2005 10:49:02 -0500
Valdis.Kletnieks () vt edu wrote:
Just a thought here... don't know if there are any complications with my suggestion here, but -- why not go the other route and clear the video memory as X is shutting down, such that there's no stale data left in the buffers?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). 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. 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.
-Barry _______________________________________________ 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? 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)