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Hello,

I've been hacking some framebuffer drivers into wsdisplay conformity on 
sparc64 and now I was wondering if they could be used on macppc too - 
especially the machfb driver for the Ultra 5 and 10 onboard video chip 
could be useful ( it supports various mach64 / Rage 3D chips ). The 
problem is, that console attachment works quite different in sparc64 
and macppc - on macppc ofb_cnattach gets called very early, sets up a 
basic framebuffer console and later attaches the rest via PCI. On 
sparc64 there's no equivalent to ofb_cnattach, it simply uses the PROM 
output or something similar until a driver takes over the console.
The macppc approach has several problems:
- - you can't use another console display driver than ofb without hacking 
machdep.c
- - if we don't use ofb as console the current code will fall back to 
serial
- - all of ofb's own shortcomings.

What I'd like to do is the following:
- - move the ofb_cnattach code somewhere else so it's always present in 
the kernel even without using the ofb driver.
- - use this code to implement the early boot console to display kernel 
output until a framebuffer driver takes over - or all the time if none 
does
- - maybe make the rest of ofb machine-independent, the other 
OpenFirmware / OpenBOOT platforms could use it.
This would allow to use other framebuffer drivers as console without 
having to worry about macppc specifics. What would remain of ofb is 
mainly ioctl() and mmap() support so we won't lose functionality.
Using other framebuffer drivers would have the following benefits:
- - acceleration. Using cache is nice but a blitter is better, especially 
on slower CPUs.
- - other resolutions than what OF sets up - not really implemented but 
it's a possibility
- - a chance to reset the console in case - for instance - an Xserver 
crashes and fails to clean up after itself
So far there are two drivers which we could use - machfb from sparc64 ( 
in -current, should work on macppc but is untested because the only ATi 
Rage chip I have is soldered on my U10's mainboard. It compiles 
flawlessly though. ) and my experimental voodoofb which supports 
Voodoo3 graphics boards.

have fun
Michael
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