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470

answers:

3

How to write directly to linux framebuffer?

+2  A: 

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

JaredPar
Also read the file Documentation/fb/framebuffer.txt (and the adjoining docs for specific drivers) in the linux kernel tree.
Andy Ross
+2  A: 

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 );
stijn
+1  A: 

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.

MarkR