From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <2a65e0b9c7b1a847d1d6baf47d33ab52@collyer.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] fileserver hardware question (Sun)
From: Geoff Collyer <geoff@collyer.net>
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Date: Fri,  6 Sep 2002 15:43:26 -0700
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Compiling and cross-compiling are pretty much the same thing on Plan
9, and there already exists a sparc compiler, so don't get hung up on
the compiler (I'm assuming you can scrounge a PC for Plan 9 at least
temporarily as a place to start from).

The first thing I'd do is make sure that I had a full description of
how the processor and related hardware work: how do you control the
MMU (in painful detail), how do you control any bus interfaces (e.g.,
SBus), do you have documentation sufficient to write a driver for the
interesting peripherals (e.g., Ethernet, video interface), what's the
layout of the physical address space?  For a Sun, this information may
be scattered, but good places to look would be the two existing Plan 9
ports to older Suns (in /n/sources/extra*), Solaris or old SunOS
include files, the parts of the Solaris kernel that Sun distributes
under its odd not-quite-open-source terms, ports of the various BSDs
and possibly Linux.  Sun's own documentation was never very helpful in
key areas (e.g., MMU) that Sun considered proprietary and valuable.
Note that Sun published at least one paper on a reference MMU design
that, as far as I know, they never actually used to build an MMU.