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Re: Linux/SGI coming

Subject: Re: Linux/SGI coming
From: Warner Losh <>
Date: Fri, 26 Apr 1996 13:53:19 -0600
In-reply-to: Your message of Fri, 26 Apr 1996 20:14:24 +0200
: MILO...

It should be relatively easy for SGI to build a MILO clone for their
bootroms.  It basically loads the kernel into memory, then jumps to
it.  The ARC BIOS stsuff is how it loads it in and sets some things
up.  You'd have to follow the tagging stuff that MILO scribbles into
high memory somehow so that the kernel can read it out.  Whether this
is done in a separate boot loader or in your code is a grey area right
now.  The ARC BIOS is a crude DOS like environment that has been
stripped down to allow files to be read off disk for the pruposes of
booting and configuration.  Some versions allow for TFTP file booting
as well.

SGI will likely also have to provide some way to read their file
system if it isn't ext2fs.  This can range from full kernel support to
an mtools like program for writing something to a efs partition (I
recall that's what sgi uses, and it isn't ufs, feel free to correct me
if I'm wrong).  Even if that was just used for the boot loader.  Also,
some disk layout issues are likely there because SGI doesn't use the
standard DOS partition scheme.  These may be answered by the
Alpha/Sparc ports, so it might not be a big issue.

: The libc implementation is based on the GNU libc which is available only
: as ELF.  My home sources are based on snapshot 960210; upgrading to the
: newest libc will 

How does one joint this development effort? :-)

: R4000 and better many of the lowlevel functions have been written to be
: SMP proof but again without SMP hardware and at this point of the project
: SMP is nothing really invest my time in.

SMP would be a fun project.  All you need is an SMP MIPS box :-(.

: The supported machines are the Mips Magnum 4000, Olivetti M700-10 (a OEM
: Magnum version) and Acer Pica 61, which is a kind of a successor type for
: the Magnum built by Acer.  All these machines have a similar DMA engine,
: Floppy, NCR53C94 SCSI and Sonic Ethernet onboard.  This SCSI/Ethernet
: hardware is currently not supported.  I thought it would be better to
: use (E)ISA hardware where drivers are very easy to port and to put my
: time on the other parts of the system.

Sniff Sniff Sniff.  Nothing about teh Deskstation rPC44? :-)  It is up
and limping at this time, but I need to upgrade to the latest kernel
to see if some of the nastier problems have been fixed, or if I need
to fix them still.  I've not tried the SCSI drivers yet, but the
floppies in 1.3.62 gave me fits.

: I think it would be great to have all this stuff on our ftp server as it
: could especially help peoples with ancient CPUs.  Andy's R4000 2.2 was
: driving me crazy ...

I know that MIPS has published a bunch of errata on the web, including
ones for the R4000.  Don't know if the 2.2 is one in the list or not,
but will check my printed copies when I get home.  None the less, it
would be good to have more complete versions of these items if they
were available.  However, I just tried the address I have for this
data, and I can't find it now.

The cross compiler stuff is fairly easy to generate.  For the SGI
platform, it should go well.  There is a howto generate cross
compilers web page hanging off the Linux-MIPS howto page that should
give you what you need to know to build the goofy things, should you
require assistance.  There are a numnber of minor gotchas, so you
might want to glance there first.


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