24 Nov
2004
24 Nov
'04
6:25 a.m.
der Mouse wrote:
<snip>
>Does anyone
know what are the real technical differences between
>sun4, sun4c and sun4m subarchitectures of SPARC from the viewpoint
>of an OS kernel writer? [...] Net/OpenBSD has a unified SPARC
>kernel, [...]
I just had a quick look at the NetBSD code. The biggest differences
seem to be in the pmap, which deals with the MMU; there are other
checks for SUN4 vs SUN4M vs SUN4C scattered around, but they are mostly
various drivers that know things like "this device appears attached to
obio only on 4c machines". It's possible to build a kernel supporting
any desired subset of the three types; if you build a kernel supporting
more than one type, you will pay a marginal speed penalty since some
things will make run-time checks for the architecture, checks which are
effectively done at compile time in a single-architecture kernel. You might want to check it before suggesting it. I
just had a look and
found nothing of any real use to an OS writer. It talks only in
generalities far too vague to write code to.
First, I lost the original post by MS, so the attribution is fuzzy.
Sorry. Sue me. ;)
Second, I'm certain that the core technology of the 32-bit SPARC
processors is open and published. There are even a couple of FPGA
implementations of the early ones out there.
I don't know where the specific docs are, but I can ask if it sounds
relevant.
Doc