Ethical Hacking Learn to find vulnerabilities before the bad guys do! Gain real world hands on hacking experience in our state of the art hacking lab. Course designed and taught by expert instructors with years of penetration testing experience. 12 student maximum in every class. Certification attempt included in every package. | Computer Forensics Training at InfoSec Institute Gain the in-demand skills of a certified computer examiner, learn to recover trace data left behind by fraud, theft, and cybercrime perpetrators. Discover the source of computer crime and abuse at your organization so that it never happens again. All of our class sizes are guaranteed to be 12 students or less to facilitate one-on-one interaction with one of our expert instructors. |

| Subject: | Re: [Full-Disclosure] Xfree86 video buffering? |
|---|---|
| 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
| Previous by Date: | RE: [Full-Disclosure] Please help me update my address book on Ringo, Michael Scheidell |
|---|---|
| Next by Date: | [Full-Disclosure] Re: Xfree86 video buffering?, Riad S. Wahby |
| Previous by Thread: | RE: [Full-Disclosure] Xfree86 video buffering?, Allan |
| Next by Thread: | [Full-Disclosure] Re: Xfree86 video buffering?, Riad S. Wahby |
| Indexes: | [Date] [Thread] [Top] [All Lists] |