Sunday, July 26, 2009

Local "DOS" against the NVidia Linux driver

Because of a bug, I found out that looping on glClear causes very painful results with the NVidia Linux driver. It makes the desktop unusable, updating only every 2 seconds, and no events will reach any program. Only way to get out of it is to switch to a tty, then events seem to be transmitted, and the program will be exited. X crashed once when I switched to a tty, tho. Try out on your own risk.

EDIT: Warning: Seems that I didn't fix the bug in the program, so I got into the same situation again (however, my program runs a few gl statements in between every glClear) and the machine became so unresponsive that I couldn't even switch to a tty (had no second computer to ssh in with, that would likely have solved it). I repeat, run it at your own risk.

Here's a test-case:
#include <sdl.h>
#include <gl.h>

int main(int argc, char *argv[])
SDL_Surface *screen;
int i = 0;


screen = SDL_SetVideoMode( 640, 480, 0, SDL_OPENGL | SDL_GL_DOUBLEBUFFER );


while (1)

return 0;

Note that I am running a rather old version of the NVidia Linux driver, 173.14.09, they could very well have fixed this in newer versions.

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