In attempting to write directly to the graphics frame buffer /dev/fb0 , (Ubuntu 12.04) , the graphics screen does not change.

Has Ubuntu 12.04 invalidated the use of /dev/fb0 , or does it need to be activated in some way ?

  • 2
    Can you provide a bit more detail how you do the "writing"? (script, program, command line, etc)
    – John Siu
    Dec 13, 2012 at 16:19
  • @John I tried the method described here with the same results: nothing appears on the screen. I also tried shutting off the GUI, and switching to an alternate console with Ctrl+Alt+F1, but nothing appears on the screen. I looked at using SDL, but it uses BitBlt for everything which will be too slow for individual pixel writes to the screen.
    – Brian
    Dec 13, 2012 at 18:46
  • Is it possible the screen re-fresh rate so fast that "cover" your screen update.
    – John Siu
    Dec 13, 2012 at 20:37
  • @John No , the area size being written to the screen was 200x200 pixels and there was not even a flicker. The driver is non-accelerated and you would see that flash if it were actually writing to the screen. During the various tests of turning various things on and off in Ubuntu , somewhere along the line /dev/fb0 vanished , but the thing that made me suspicious that Ubuntu is not using /dev/fb0 at all is because the GUI was present and functioned normally without /dev/fb0. I didn't even notice until when trying to open /dev/fb0 using the test program it failed to open the file.
    – Brian
    Dec 14, 2012 at 2:59

1 Answer 1


Had to do a 2nd ioctl() to ACTIVATE the frame buffer, then it worked.

/* Refresh buffer manually */
if(0 > ioctl(fd, FBIOPUT_VSCREENINFO, &vi)) {
  printf("Failed to refresh\n");
  return -1;
  • 1
    Please mark this answer as 'accepted' so everyone knows that you have solved your problem.
    – user37607
    Oct 9, 2013 at 11:14

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