Subject: Re: the prom: to map or not to map
To: None <netbsd-ports@NetBSD.ORG>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: netbsd-ports
Date: 06/12/1997 07:11:03
> I would also be interested if someone could comment on the sparc and
> sun3 ports use of the prom.

AFAIK they don't use the PROM except during boot and shutdown, except
for systems with certain framebuffers, where the PROM routines get used
for console output.  The bootblocks use the PROM routines to read in
the kernel, I believe, and at least on the SPARC the kernel has to do
callbacks to the PROM to set up VM mappings in other contexts.  (The
kernel can't do this itself because one can't set up mappings in
non-current contexts, but one can't run in a context that doesn't have
the kernel mapped in.  Apparently the hardware has a mode where all
memory references go to the PROM, which makes it easy - for the PROM.)

I'm sure someone who really knows those ports will correct me if I'm
wrong here. :)

					der Mouse

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