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。