On Fri, 15 Dec 1995, Andrew Gillham wrote:

> Hmm, to be honest, I don't understand why NetBSD/mac68k needs MODE32
> at all.  From what I can tell MODE32 is supposed to make the ROMs 32bit
> clean, yet NetBSD only uses the ADB ROM code?  So, if MODE32 is required
> to correctly setup the PMMU mappings, why can't that be done by the
> kernel?  

Dunno.  It'd make the kernel a lot bigger.  Maybe if the kernel were 
split into several modules, with the booter assembling them at boot time 
for the particular system into the netbsd file.  Complicated and 
time-consuming, but worth considering for complete machine-independence.  
The only changes to add a new feature would be replacing a single module 
or adding a new one and then changing config.sys :-) on the boot disk.  
Besides, it would also make it tidy for people using one system at all 
times -- he/she could just delete whatever modules weren't needed for 
that system.

> > It's gonna take some work.  I think it could be done pretty easily for 
> > systems that don't require MODE32 and have already been set for b/w.  If 
> > you assume those two things (and still maintain a booter for people who 
> > *need* MODE32 until its code becomes integrated), the new booter wouldn't 
> > be bad.
> 
> Seems like the only requirement should be that you know whether the
> video is in 1bit/4bit/8bit mode?  AFAIK I'm in 8bit at the happy mac
> screen, as that is what is configured.  Perhaps it is automatically in
> 1bit there?  I guess I'll have to add a putpixel routine.

I pretty much think that you're right about the first part, anyway.  Of 
course, I don't know about the second.  I think it's in whatever mode is 
set in the PRAM.  The MacOS checks it at more than one point, too.  If 
the PRAM gets erased, (at least on PowerMacs) it recreates it at the end 
of the boot.  Much to the surprise of the Apple Technical ppl, mine even 
switched back into hi-res mode!  Weird, huh.

The 1 bit stuff seems to only be a problem on certain systems.  The IIsi, 
for instance, can boot in 256 color mode as well, albeit a *lot* slower.  
That's the biggest difference is in the way greater bit depths hog speed 
and memory.  :-(  Basically, if for no other reason than the speed 
increase, NetBSD should probably set the monitor to 1 bit.  It could 
always change it back for running X, etc.

Later,

 /---------------------------------------------------------------------\
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