[TUHS] Origins of the frame buffer device

Arno Griffioen via TUHS tuhs at tuhs.org
Wed Mar 8 23:17:47 AEST 2023


On Wed, Mar 08, 2023 at 01:51:10PM +0100, Paul Ruizendaal via TUHS wrote:
> It is then surprising that Linux did not come up with /dev/fbdev until 1999, 
> especially in view of the importance of X to the early Linux developers. 

The PC/intel 'birthplace' of Linux had the advantage that the video hardware
always had an ASCII mode, so from that viewpoint there was no need for 
any fb interface initially to get things going.

If I remember correctly, things like SCO Unix also did not use any fb-style
interface for their X11.

> Maybe the reason was that the headache of video drivers was delegated to 
> the XFree community.

Correct. There was definitely a sense that keeping all the graphics bits out 
of the kernel and just letting Xfree open /dev/mem and do it's magic was the 
preferred way. Also meant that Xfree wasn't waiting on kernel bits and 
vice-versa and could keep going in parallel.

Unlike today where there's only a few cards/manufacturers left, we had 
hundreds of similar-but-not-quite-the-same PC videocards on the market,
so it was an understandable sentiment as change was fast and frequent
on the Xfree end.

The FBdev idea really started brewing because of the non-intel Linux ports 
that did not have the luxury of a built-in ASCII-capable 'console' so needed 
to get something going there (after initial porting with serial output).

Something was needed 'in kernel' even for a plain console on the framebuffer 
and to keep it from falling apart some sort of general interface for some sort 
of generic X11 (even un-accelerated) as well.

Most of the non-PC framebuffer hardware was too 'obscure' for Xfree to spend 
much time on as well..

The Linux/M68k port with Geert being very active here and really pushing to 
getting a more generalised display setup going that would work on the wildly 
different framebuffer hardware between all the m68k platforms but make 
basically use of 1 simple X server that didn't need to know that much
about the hardware. 

Ultimately this led to the general FBdev project for all platforms.

							Bye, Arno.


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