fb.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>

// application entry point
int main(int argc, char* argv[])
{
  int fbfd = 0; // framebuffer filedescriptor
  struct fb_var_screeninfo var_info;

  // Open the framebuffer device file for reading and writing
  fbfd = open("/dev/fb0", O_RDWR);
  if (!fbfd) {
    printf("Error: cannot open framebuffer device.\n");
    return(1);
  }
  printf("The framebuffer device opened.\n");

  // Get variable screen information
  if (ioctl(fbfd, FBIOGET_VSCREENINFO, &var_info)) {
    printf("Error reading variable screen info.\n");
  }
  printf("Display info %dx%d, %d bpp\n", 
         var_info.xres, var_info.yres, 
         var_info.bits_per_pixel );

  // close file  
  close(fbfd);
  
  return 0;

}