如何配置UBUTNU启用帧缓存，是一个很好的应用实例，今天我写写这个问题

设置开机进入文本模式

（1）、修改启动菜单配置文件

# vi /etc/default/grub

修改

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

为：

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash text vga=0x311" 

注释：

这里text表示进入文本模式，vga=0x311表示使用Framebuffer显示驱动，

0x311是指示色深和分辨率的参数

      | 640x480 800x600 1024x768 1280x1024

------+-----------------------------------------------------

256   | 0x301     0x303     0x305       0x307

32k   | 0x310     0x313     0x316       0x319

16bpp | 0x311     0x314     0x317       0x31A

16M   | 0x312     0x315     0x318       0x31B

（2）、更新启动菜单

$ sudo update-grub

写入到/boot/grub/grub.cfg

（3）、修改initramfs

$ sudo gedit /etc/initramfs-tools/modules

添加：

vesafb

（4）、

$ sudo gedit /etc/modprobe.d/blacklist-framebuffer.conf

用#注释以下行

# blacklist vesafb

（5）、更新initramfs

$ sudo update-initramfs -u

（生成新的initrd）

（6）、

然后重启机器，即可进入Framebuffer

如果要切换回X11，可以输入：

$ startx

（7）、图形界面切换到字符界面

A、atl+ctrl+shift+F1

B、ctrl+c

以下是帧缓存的测试程序。

#include

#include

#include

#include

#include

int main()

{

    int fbfd = 0;

    struct fb_var_screeninfo vinfo;

    struct fb_fix_screeninfo finfo;

    long int screensize = 0;

    char *fbp = 0;

    int x = 0, y = 0;

    long int location = 0;

    // Open the file for reading and writing

    fbfd = open("/dev/fb0", O_RDWR);

    if (0 > fbfd) {

        printf("Error: cannot open framebuffer device.\n");

        exit(1);

    }

    printf("The framebuffer device was opened successfully.\n");

    // Get variable screen information

    if (0 > ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {

        printf("Error reading variable information.\n");

        exit(3);

    }

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

    // Figure out the size of the screen in bytes

    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;

    // Map the device to memory

    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,

                       fbfd, 0);

    if ( fbp == MAP_FAILED) {

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

        exit(4);

    }

    printf("The framebuffer device was mapped to memory successfully.\n");

unsigned short *lcd = (unsigned short *)fbp;

// Figure out where in memory to put the pixel

    for (int x = 0; x < vinfo.xres; x++)

{

for (int y = 0; y < vinfo.yres; y++) 

        {

*lcd++ = (0x1F << 11);

//*lcd++ = (0x3F << 5);

//*lcd++ = (0x1F);

        }

}

munmap(fbp, screensize);

    printf("The framebuffer device was munmapped to memory successfully.\n");

    close(fbfd);

    printf("The framebuffer device was closed successfully.\n");

    return 0;

} 

看到成功了吗，大家可以试一下。