Difference between sun4, sun4c and sun4m subarchitectures

From: Doc Shipley <doc_at_mdrconsult.com>
Date: Wed Nov 24 14:25:11 2004

der Mouse wrote:

>>>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.

<snip>

> 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
Received on Wed Nov 24 2004 - 14:25:11 GMT