Subject: Linux from Scratch

From: Jim Gifford <[email-masked]>
Date: Wed, 09 Feb 2005 20:48:57 -0800

I have updated my RaQ2 build for Linux from Scratch to most of the 
latest packages for the RaQ2. A question was raised by some other 
memebers of the Linux from Scratch group, that frankly I didn't have the 
answers for. I appreciate your feedback on these questions.

1 - Will the build method I have currently work with any MIPS processor 
based machine, with the exception of the bootloader?

2 - Is there a bootloader for MIPS that will work on every machine, or 
is different for every MIPS based machine's firmware? If so any examples 
out there how to implement?

Thank you for your time and assistance

-- 
----
Jim Gifford
[email-masked]

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From: Stuart Longland <[email-masked]>
Date: Thu, 10 Feb 2005 23:36:25 +1000

> based machine, with the exception of the bootloader?

The bulk of it would be largely the same -- however there would be a
difference in that endianness, ABIs and ISAs have to be considered.

e.g.
Cobalt Servers are Little Endian running RM523[01] CPUs (MIPS IV ISA).
All (MIPS-based) SGI machines are Big Endian, mainly with either MIPS
III or MIPS IV class CPUs.

Therefore you use mips-unknown-linux-gnu as the HOST on SGI boxes, and
mipsel-unknown-linux-gnu on Cobalts.  (Some even use
mips64-unknown-linux-gnu)

> out there how to implement?

Okay, a lot of MIPS machines implement the ARCs firmware, but still
there's a big variety of machines there -- so making one bootloader
support them all would be an outright nightmare.  Having said that,
there are several bootloaders that do get used across multiple machines.
  Some that come to mind:

- CoLo (the Cobalt Loader) for Cobalt servers
- ARCBoot for SGI machines
- U-Boot
- YAMON

and there are likely many more.  They've all got their own differences
-- just to give you an idea, have a look at my copy of the Gentoo/MIPS
handbook[2] -- specifically the bootloader section[3].  This version
covers setting up both Cobalt servers and SGI machines with Gentoo
Linux.  As you can see, there's a big difference between the machines.

Anyway, I hope that's answered some of your questions. :-)
--
+-------------------------------------------------------------+
| Stuart Longland -oOo- http://stuartl.longlandclan.hopto.org |
| Atomic Linux Project     -oOo-    http://atomicl.berlios.de |
| - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
| I haven't lost my mind - it's backed up on a tape somewhere |
+-------------------------------------------------------------+
Footnotes:
1. Note that the IP12 and it's R4k cousin, the IP20 are currently
unsupported in Linux at this time -- although people are working on that :-)
2. Got the clipboard applet ready?  This is a long one:
<http://www.longlandclan.hopto.org/~stuartl/gentoo/docs/index.php/gentoo-doc/en/handbook/handbook-mips.xml>
3. Configuring the Bootloader:
<http://www.longlandclan.hopto.org/~stuartl/gentoo/docs/index.php/gentoo-doc/en/handbook/handbook-mips.xml?part=1&chap=10>
... and yes, eventually this will be put on the main Gentoo site...
pending bug #81072: <http://bugs.gentoo.org/show_bug.cgi?id=81072>