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Old 01-17-2007, 02:38 PM   #1
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Registered: Apr 2003
Location: nottingham england
Distribution: Gentoo
Posts: 2,672

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Framebuffer graphics WITHOUT /dev/fb#

Hey Guys...

Im coding a 2d game engine for the AMD Geode-LX embedded system under Linux.

AMD Provide drivers patches for the Kernel and Xorg to use what little hardware acceleration this device has to offer..

These Patches include
1) X11 Graphics Driver 9 would prefere not to use X11 )
( Works Well, But i was hoping to keep the system small, and rediuce the overhead )

2) Frame Buffer Driver.... ( preffered choice )
HOWEVER... this framebuffer driver appears to be broken and in-complete
with absolutly no documentation.

The kernel will happily use this framebuffer driver to devliver the standard 'framebuffer console complete with penguin logo'

but any attempts to use /dev/fbX fail miserably....

IOCTL's work fine as expected, allowing me to pan the display / change screen_var_info...

however, ad attempt to read / write to /dev0 fails !!

linux reports the block device as being of size zero.

all attempts to mmap it fail.

fbset reports the framebufer address as NIL.

Which Leads me to my final question...

The kernel is able to take advantage of this hardware accelerated framebuffer ( it can dump text to the screen far faster than the generic vesa framebuffer )

it seemss to just be the block device driver that is borked !

from userspace.... is there a way of performing the usual framebuffer activities without the /dev/fb0 block device ?????

I am running Linux 2.6.11, currently with a gentoo environment ( but later plan to create a nice customised distro with help from LFS )

Old 02-17-2007, 07:45 PM   #2
Registered: Dec 2005
Location: New York
Distribution: Debian/GNU
Posts: 235

Rep: Reputation: 31
hack X?

anyone know if /dev/fb0 et al work in linux 2.6? I haven't with framebuffer stuff since '99, but back then I had to hack an X driver to provide direct access to the video framebuffer (and, of course, run everything as root, not a commercial-friendly solution).

If the /dev files don't work, I'd suggest figuring out how to comile Xorg (if you haven't already) and start looking into the
video driver code.

again, this advice is based on what I did 8 years ago.




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