linux中使用mmap函数出现 No such device错误

[圣主天君]

我在编写lcd液晶程序的时候，让液晶显示一张bmp格式图片，主体代码如下，当运行到mmap函数时就出错了，用perror查看错误，提示No such device，请问各位大牛们这是什么问题？

int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
struct fb_bitfield red;
struct fb_bitfield green;
struct fb_bitfield blue;

fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd)
{
printf("Error: cannot open framebuffer device.\n");
exit(1);
}

if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo))
{
printf("Error:reading fixed information.\n");
exit(2);
}

if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
{
printf("Error: reading variable information.\n");
exit(3);
}

printf("R:%d,G:%d,B:%d \n", vinfo.red.length, vinfo.green.length, vinfo.blue.length );

printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel );
xres = vinfo.xres;
yres = vinfo.yres;
bits_per_pixel = vinfo.bits_per_pixel;

screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("screensize=%ld byte\n",screensize);

fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
perror("错误：");[/color]
if ((int)fbp == -1)
{

printf("Error: failed to map framebuffer device to memory.\n");
exit(4);
}