Writes to FrameBuffer /dev/fb0 do not seem to change graphics screen

Question

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 ?

Answer 1

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

/* Refresh buffer manually */
vi.activate |= FB_ACTIVATE_NOW | FB_ACTIVATE_FORCE;
if(0 > ioctl(fd, FBIOPUT_VSCREENINFO, &vi)) {
  printf("Failed to refresh\n");
  return -1;
}