How to write directly to linux framebuffer?

Question

the german wiki lists a complete example http://de.wikipedia.org/wiki/Framebuffer#Linux-Framebuffer — relascope, Apr 20 '15 at 23:19

stijn · Accepted Answer · 2009-10-07T07:55:59.090

look at FBIOPUT_VSCREENINFO, ioctl and mmap

(I have the code but not at this pc, sorry)

edit: this should get you started

  //open file descriptor and get info
inf fdScreen = open( "devicename", O_RDWR );
fb_var_screeninfo varInfo;
ioctl( fdScreen, FBIOGET_VSCREENINFO, &varInfo );

  //set resolution/dpi/color depth/.. in varInfo, then write it back
ioctl( fdScreen, FBIOPUT_VSCREENINFO, &varInfo );

  //get writable screen memory; unsigned short here for 16bit color
unsigned short* display = mmap( 0, nScreenSize,
                                PROT_READ | PROT_WRITE, MAP_SHARED, fdScreen, 0 );

score 6 · Answer 2 · answered Oct 07 '09 at 06:21

6

Basically you open /dev/fb0, do some ioctls on it, then mmap it. Then you just write to the mmap'd area in your process.

answered Oct 07 '09 at 06:21

MarkR

61,128
14
112
147

score 4 · Answer 3 · edited Jun 14 '21 at 23:11

4

Are you looking to write a device driver? If so check out this HowTo guide

edited Jun 14 '21 at 23:11

hammus

2,602
1
16
36

answered Oct 06 '09 at 17:44

JaredPar

703,665
143
1,211
1,438

Also read the file Documentation/fb/framebuffer.txt (and the adjoining docs for specific drivers) in the linux kernel tree. – Andy Ross Oct 06 '09 at 19:49

How to write directly to linux framebuffer?

3 Answers3

Linked