Linux/MIPS HOWTO

Linux/MIPS HOWTO
Ralf B�chle, [email protected]
June 24, 2000

This FAQ describes the MIPS port of the Linux operating system, common
problems and their solutions, availability and more. It also tries to
be a little helpful to other people who might read this FAQ in an
attempt to find information that actually should be covered elsewhere.
______________________________________________________________________

Table of Contents

1. What is Linux/MIPS?

2. Getting this FAQ

3. What hardware does Linux/MIPS support?

3.1 Hardware platforms
3.1.1 Acer PICA
3.1.2 Baget/MIPS series
3.1.3 Cobalt Qube and Raq
3.1.4 NEC machines
3.1.5 NEC VR41xx-based platforms
3.1.6 Toshiba TMPR39xx/Philips PR31700 platforms
3.1.7 Netpower 100
3.1.8 Nintendo 64
3.1.9 Silicon Graphics Challenge S
3.1.10 Silicon Graphics Indigo
3.1.11 Silicon Graphics Indigo2
3.1.12 Silicon Graphics Indy
3.1.12.1 Strange numbers of available memory
3.1.12.2 Indy PROM related problems
3.1.12.3 ELF support in old PROM versions
3.1.12.4 Why is so much memory reserved on my Indy?
3.1.13 Silicon Graphics Origin 200 and 2000
3.1.14 Silicon Graphics Onyx 2
3.1.15 Silicon Graphics Power Series
3.1.16 Serial console on SGI machines
3.1.17 Other Silicon Graphics machines
3.1.18 Sony Playstation
3.1.19 SNI RM200C
3.1.20 SNI RM200
3.1.21 SNI RM300C
3.1.22 SNI RM400
3.1.23 SNI RW320
3.1.24 Algorithmics P4032
3.1.25 Algorithmics P5064
3.1.26 DECstation series
3.1.27 Mips Magnum 4000 / Olivetti M700-10
3.1.28 MIPS Magnum 4000SC
3.2 Processor types
3.2.1 R2000, R3000 family
3.2.2 R6000
3.2.3 R4000 and R5000 family
3.2.4 R8000
3.2.5 R10000
3.3 Hardware we're never going to support
3.3.1 IBM RS6000
3.3.2 VaxStation
3.3.3 SGI VisPC
3.3.4 Motorola 68k based machines like the Iris 3000

4. Linux distributions.

4.1 RedHat
4.2 Debian

5. Linux/MIPS net resources.

5.1 Anonymous FTP servers.
5.2 Anonymous CVS servers.
5.3 Web servers.
5.4 Web CVS server.
5.5 Mailing lists.
5.6 IRC channel.

6. Installation of Linux/MIPS and common problems.
6.1 NFS booting fails.
6.2 Self compiled kernels crash when booting.
6.3 Booting the kernel on the Indy fails with PROM error messages
6.4 Where can I get the little endian firmware for my SNI?
6.5 ld dies with signal 6
6.6 My machine doesn't download the kernel when I try to netboot
6.7 Bug in DHCP version 2

7. Milo

7.1 Building Milo
7.2 Pandora

8. Loadable Modules

9. How do I setup a crosscompiler?

9.1 Available binaries
9.2 Building your own crosscompiler
9.3 Diskspace requirements
9.4 Byte order
9.5 Configuration names
9.6 Installation of GNU Binutils.
9.7 Assert.h
9.8 Installing the kernel sources
9.9 First installation of egcs
9.10 Test what you've done so far
9.11 Installing GNU libc
9.12 Building egcs again
9.13 Should I build the C++, Objective C or F77 compilers?
9.14 Known problem when crosscompiling
9.14.1 IRIX crashes
9.14.2 Resource limits on System V based hosts
9.15 GDB

10. Related Literature

10.1 See MIPS Run
10.2 The MIPS Programmer's Handbook
10.3 Computer Architecture - A Quantitative Approach
10.4 UNIX System V ABI MIPS Processor Supplement

______________________________________________________________________

1. What is Linux/MIPS?

Linux/MIPS is a port of the widespread UNIX clone Linux to the MIPS
architecture. Linux/MIPS is running on a large number of technically
very different systems ranging from little embedded systems and
servers to large desktop machines and servers that, at least at the
time when they were introduced into the market, were the best of their
class.

Linux/MIPS advantages over other operating systems at this time are

� The entire Linux system consists only of Free Software.

� Excellent Price/Performance ratio.

� Availability of large amounts of software of which a large part
again is Free Software.

� Binary compatibility across a growing number of platforms.

� Small footprint making Linux/MIPS suitable for many embedded
systems.

In short, Linux has been designed and ships with Fahrvergn�gen.
However as usual your mileage may vary and you should examine Linux's
suitability for your purpose which purpose this document tries to
serve.

2. Getting this FAQ

You can download this document in various formats:

� The HTML version <http://oss.sgi.com/mips/mips-howto.html>

� The text version <http://oss.sgi.com/mips/mips-howto.txt>

� The Postscript version <http://oss.sgi.com/mips/mips-howto.ps>

� The Linux-Doc SGML version. <http://oss.sgi.com/mips/mips-
howto.sgml>

This FAQ is also available as SGML source code via anonymous CVS from
oss.sgi.com. The archive also has a Makefile which will translate it
into various formats. An ASCII version is regularly being posted via
comp.os.linux.answers and the other Linux HOWTO channels.

3. What hardware does Linux/MIPS support?

3.1. Hardware platforms

Many machines are available with a number of different CPU options of
which not all are currently supported. Please check section
``Processor Types'' to make sure your CPU type is supported. This is
a listing of machines that are running Linux/MIPS, systems to which
Linux/MIPS could be ported or systems that people have an interest in
running Linux/MIPS.

3.1.1. Acer PICA

The Acer PICA is derived from the Mips Magnum 4000 design. It has a
R4400PC CPU running at 133Mhz or optionally 150Mhz plus a 512kb
(optionally 2mb) second level cache; the Magnum's G364 gfx card was
replaced with a S3 968 based one. The system is supported with the
exception of the X server.

3.1.2. Baget/MIPS series

The Baget series includes several boxes which have R3000 processors:
Baget 23, Baget 63, and Baget 83. Baget 23 and 63 have BT23-201 or
BT23-202 motherboards with R3500A (which is basically a R3000A chip)
at 25 MHz and R3081E at 50 MHz respectively. The BT23-201 board has
VME bus and VIC068, VAC068 chips as system controllers. The BT23-202
board has PCI as internal bus and VME as internal. Support for
BT23-201 board has been done by Gleb Raiko ([email protected])
and Vladimir Roganov ([email protected]) with a bit help from Serguei
Zimin ([email protected]). Support for BT23-202 is under development
along with Baget 23B which consists of 3 BT23-201 boards with shared
VME bus.

Baget 83 is mentioned here for completeness only. It has only 2mb RAM
and it's too small to run Linux. The Baget/MIPS code has been merged
with the DECstation port; source for both is available at
<http://decstation.unix-ag.org/>.

3.1.3. Cobalt Qube and Raq

The Cobalt Qube product series are low cost headless server systems
based on a IDT R5230. Cobalt has developed its own Linux/MIPS variant
to fit the special requirements of the Qube as well as possible.
Basically the Qube kernel has been derived from Linux/MIPS 2.1.56,
then backported to 2.0.30 for stability's sake, then optimized.
Cobalt kernels are available from Cobalt's ftp site
<http://www.cobaltnet.com>. The Cobalt Qube support has never been
integrated into the official Linux/MIPS 2.1.x kernels.

3.1.4. NEC machines

The NEC uniprocessor machines are OEM Acer PICA systems, see that
section for details. The SMP systems are different from that. The
Linux/MIPS developers have no technical documentation as necessary to
write an OS. As long as this does not change this will pretty much
stay a show stopper preventing a port to NEC's SMP systems.

3.1.5. NEC VR41xx-based platforms

The Linux VR project is porting Linux to devices based on the NEC
VR41xx microprocessors. Many of these devices were originally
designed to run Windows CE. The project has produced working kernels
with basic drivers for the Vadem Clio, Casio E-105, Everex Freestyle,
and more. For more information please see <http://linux-vr.org/>.

3.1.6. Toshiba TMPR39xx/Philips PR31700 platforms

Similar to the VR41xx, devices with these processors were originally
intended for running Windows CE. However, there are working kernels
with basic drivers for Sharp Mobilon and the Compaq C-Series. Support
for more devices is under construction. The code is part of the Linux
VR project and as such more information can be found at
<http://linux-vr.org/>.

3.1.7. Netpower 100

The Netpower 100 is apparently an Acer PICA in disguise. It should
therefore be supported but this is untested. If there is a problem
then it is probably the machine detection.

3.1.8. Nintendo 64

The Nintendo 64 is R4300 based game console with 4mb RAM. Its
graphics chips were developed by Silicon Graphics for Nintendo. Right
now this port has pipe dream status and will continue to be in that
state until Nintendo decides to publish the necessary technical
information. The question remains as to whether this is a good idea.

3.1.9. Silicon Graphics Challenge S

This machine is very similar to the Indy; the difference is that it
doesn't have a keyboard and a GFX card but has an additional SCSI
WD33C95 based adapter. This WD33C95 hostadapter is currently not
supported.

3.1.10. Silicon Graphics Indigo

This machine is only being mentioned here because occasionally people
have confused it with Indys or the Indigo 2. The Indigo is a
different, R3000 based architecture however and not yet unsupported.

3.1.11. Silicon Graphics Indigo2

This machine is the successor to the Indigo and is very similar to the
Indy. It is now supported, however it is lacking in several areas.
You will have to use serial console. If you have a Indigo2 and still
want to run Linux on it, contact either Florian Lohoff
([email protected]) or Klaus Naumann ([email protected]) .

3.1.12. Silicon Graphics Indy

The Indy is currently the only (mostly) supported Silicon Graphics
machine. The only supported graphics card is the Newport card aka
``XL'' graphics. The Indy is available with a large number of CPU
options at various clock rates all of which are supported. There's
also a X server available now written by Guido Guenther
([email protected]). If you're able to use the Newport console
on your Indy it should be possible to also use this X server. It's
based on XFree86 4.0 and currently running at snail speed but seems to
work quite ok. If you want to try it take a look at
<http://honk.physik.uni-konstanz.de/~agx/mipslinux/x/> .

3.1.12.1. Strange numbers of available memory

On bootup the kernel on the Indy will report available memory with a
message like

Memory: 27976k/163372k available (1220k kernel code, 2324k data)

The large difference between the first pair of numbers is caused by a
128mb area in the Indy's memory address space which mirrors up to the
first 128mb of memory. The difference between the two numbers will
always be about 128mb and does not indicate a problem of any kind.
Kernels since 2.3.23 don't count this 128mb gap any longer.

3.1.12.2. Indy PROM related problems

Several people have reported these problems with their machines after
upgrading them typically from surplus parts. There are several PROM
versions for the Indy available. Machines with old PROM versions
which have been upgraded to newer CPU variants like a R4600SC or
R5000SC module can crash during the self test with an error message
like

Exception: <vector=Normal>
Status register: 0x30004803<CU1,CU0,IM7,IM4,IPL=???,MODE=KERNEL,EXL,IE>
Cause register: 0x4000<CE=0,IP7,EXC=INT>
Exception PC: 0xbfc0b598
Interrupt exception
CPU Parity Error Interrupt
Local I/O interrupt register 1: 0x80 <VR/GIO2>
CPU parity error register: 0x80b<B0,B1,B3,SYSAD_PAR>
CPU parity error: address: 0x1fc0b598
NESTED EXCEPTION #1 at EPC: 9fc3df00; first exception at PC: bfc0b598

In that case you'll have to upgrade your machine's PROMs to a newer
version or go back to an older CPU version. Usually R4000SC or
R4400SC modules should work in that case. Just to be clear, this is a
problem which is unrelated to Linux. It's only mentioned here because
several Linux users have asked about it.

3.1.12.3. ELF support in old PROM versions

Old PROM versions don't know about the ELF binary format which the
Linux kernel uses, that is can't boot Linux directly. The preferable
solution for this is of course a PROM upgrade. Alternatively you can
use Sash of IRIX 5 or newer to boot the kernel. Sash knows how to
load ELF binaries and doesn't care if it's an IRIX or Linux kernel.
Simply type ``Sash'' to the prom monitor. You should get another
shell prompt, this time from Sash. Now launch Linux as usual.

Sash can read EFS or XFS filesystems or read the kernel from bootp /
tftp. That means if you intend to use Sash for booting the kernel
from local disk you'll still have to have a minimal IRIX installation
on your system.

3.1.12.4. Why is so much memory reserved on my Indy?

On bootup the `Memory: ...' message on an Indy says that there is
128mb of RAM reserved. That is ok; just like the PC architecture has
a gap in its memory address space between 640kb and 1024kb, the Indy
has a 128mb-sized area in its memory map where the first 128mb of its
memory is mirrored. Linux knows about it and just ignores that
memory, thus this message.

3.1.13. Silicon Graphics Origin 200 and 2000

Ralf B�chle ([email protected]) and a team of SGI employees are currently
working on a port to the Origin 200. While still in it's early stages
it's running in uniprocessor and multiprocessor mode and has drivers
for the builtin IOC3 Ethernet and SCSI hostadapters. The code is
available in the Linux/MIPS CVS tree.

3.1.14. Silicon Graphics Onyx 2

The Onyx 2 is basically an Origin 2000 with additional graphics
hardware. As of now about Linux support for the graphics hardware has
not yet been decieded. Aside of that Linux should run just as well as
on a normal headless Origin 2000 configuration.

3.1.15. Silicon Graphics Power Series

This is a very old series of R3000 SMP systems. There is no hardware
documentation for these machines, few of them exist anymore, the
hardware is weird. In short, chances that Linux will ever run on them
are approximating zero. Not that we want to disencourage takers ...

3.1.16. Serial console on SGI machines

Make sure the kernel you're using includes the appropriate driver for
a serial interface and serial console. Set the console ARC
environment variable to either the value d1 or d2 for Indy and
Challenge S depending on which serial interface you're going to use as
console.

If you have the problem that all kernel messages appear on the serial
console on bootup but everything is missing from the point when init
starts, then you probably have the wrong setup for your /dev/console.
You can find more information about this in the Linux kernel source
documentation; it's in /usr/src/linux/Documentation/serial-console.txt
if you have the kernel source installed.

3.1.17. Other Silicon Graphics machines

At this time no other Silicon Graphics machine is supported. This
also applies to the very old Motorola 68k based systems.

3.1.18. Sony Playstation

The Sony Playstation is based on an R3000 derivative and uses a set of
graphics chips developed by Sony themselves. While the machine in
theory would be capable of running Linux, a port is difficult, since
Sony so far hasn't provided the necessary technical information. This
still leaves the question of whether the port would be worthwhile. So
in short, nothing has happend yet even though many people have shown
their interest in trying Linux on a Playstation so far.

3.1.19. SNI RM200C

In contrast to the RM200 (see below) this machine has EISA and PCI
slots. The RM200 is supported with the exception of the availability
of the onboard NCR53c810A SCSI controller.

3.1.20. SNI RM200

If your machine has both EISA and PCI slots, then it is an RM200C;
please see above. Due to the slight architectural differences of the
RM200 and the RM200C this machine isn't currently supported in the
official sources. Michael Engel ([email protected])
has managed to get his RM200 working partially but the patches haven't
yet been included in the official Linux/MIPS sources.

3.1.21. SNI RM300C

The RM300 is technically very similar to the RM200C. It should be
supported by the current Linux kernel, but we haven't yet received any
reports.

3.1.22. SNI RM400

The RM400 isn't supported.

3.1.23. SNI RW320

This machine is a OEM variant of the SGI Indigo and therefore also
still unsupported.

3.1.24. Algorithmics P4032

The Algorithmics P4032 port is at the time of this writing still
running Linux 2.1.36.

3.1.25. Algorithmics P5064

The P5064 is basically an R5000-based 64bit variant of the P4032. A
port is ongoing.

3.1.26. DECstation series

During the late 80's and the early 90's Digital (now Compaq) built
MIPS based Workstations named DECstation resp. DECsystem. Other x86
and Alpha based machines were sold under the name DECstation, but
these are obviously not subject of this FAQ. Support for DECstations
is still under development, started by Paul M. Antoine. These days
most of the work is done by Harald Koerfgen
([email protected]) and others. On the Internet, DECstation-
related information can be found at <http://decstation.unix-ag.org/>.

The DECstation family ranges from the DECstation 2100 with an
R2000/R2010 chipset at 12 Mhz to the DECstation 5000/260 with a 60 MHz
R4400SC.

The following DECstation models are actively supported:

� 2100, codename PMAX

� 5000/xx (Personal DECstation), codename MAXine

� 5000/1xx, codename 3MIN

� 5000/200, codename 3MAX

� 5000/2x0, codename 3MAX+

� 5900/2x0 (identical to the 3MAX+).

These DECstation models are orphaned because nobody is working on
them, but support for these should be relatively easy to achieve.

� 3100, identical to the 2100 except the R2000A/R2010A @ 16 MHz

� 5100, codename MIPSMATE, almost identical to the 2100 but with an
R3000/R3010 chipset.

The other members of the DECstation family, besides the x86 based
ones, should be considered as VAXen with the CPU replaced by a MIPS
CPU. There is absolutely no information available about these
machines and support for them is unlikely to happen ever unless the
VAXLinux port comes to a new life. These are:
� 5400, codename MIPSFAIR

� 5500, codename MIPSFAIR2

� 5800, codename ISIS

3.1.27. Mips Magnum 4000 / Olivetti M700-10

These two machines are almost completely identical. Back during the
ACE initiative Olivetti licensed the Jazz design and marketed the
machine with Windows NT as OS. MIPS Computer Systems, Inc. itself
bought the Jazz design and marketed it as the MIPS Magnum 4000 series
of machines. Magnum 4000 systems were marketed with Windows NT and
RISC/os as operating systems.

The firmware on the machine depended on the operating system which was
installed. Linux/MIPS supports only the little endian firmware on
these two types of machines. Since the M700-10 was only marketed as
an NT machine all M700-10 machines have this firmware installed. The
MIPS Magnum case is somewhat more complex. If your machine has been
configured big endian for RISC/os then you need to reload the little
endian firmware. This firmware was originally included on a floppy
with the delivery of every Magnum. If you don't have the floppy
anymore you can download it via anonymous ftp from
<ftp://ftp.fnet.fr>.

It is possible to reconfigure the M700 for headless operation by
setting the firmware environment variables ConsoleIn and ConsoleOut to
multi()serial(0)term(). Also try the command listdev which will show
the available ARC devices.

In some cases, like where the G364 graphics card is missing but the
console is still configured to use normal graphics it will be
necessary to set the configuration jumper JP2 on the board. After the
next reset the machine will reboot with the console on COM2.

3.1.28. MIPS Magnum 4000SC

The Mips Magnum 4000SC is the same as a Magnum 4000 (see above) with
the exception that it uses an R4000SC CPU.

3.2.

Processor types

3.2.1. R2000, R3000 family

The R2000 is the original MIPS processor. It's a 32 bit processor
which was clocked at 8MHz back in '85 when the first MIPS processors
came to the market. Later versions were clocked faster: for
instance, the R3000 is a 100% compatible redesign of the R2000, just
clocked faster. Because of their high compatibility, where this
document mentions the R3000, in most cases the same facts also apply
to the R2000. The R3000A is basically an R2000 plus an R3010 FPU and
64k cache running at up to 40Mhz and integrated into the same chip.

Harald Koerfgen ([email protected]) and Gleb O. Raiko
([email protected]) have both independently worked on patches for
R3000 processors. The work has been merged and is integrated into the
official Linux/MIPS sources since July 1999. Actually Linux supports
R3000 processors including some derivatives like the R3081 and the
TMPR3912/PR31700

3.2.2. R6000

Sometimes people confuse the R6000, a MIPS processor, with RS6000, a
series of workstations made by IBM. So if you're reading this in hope
of finding out more about Linux on IBM machines you're reading the
wrong document.

The R6000 is currently not supported. It is a 32-bit MIPS ISA 2
processor and a pretty interesting and weird piece of silicon. It was
developed and produced by a company named BIT Technology. Later NEC
took over the semiconductor production. It was built in ECL
technology, the same technology that was and still is being used to
build extremely fast chips like those used in some Cray computers.
The processor had its TLB implemented as part of the last couple of
lines of the external primary cache, a technology called TLB slice.
That means its MMU is substantially different from those of the R3000
or R4000 series, which is also one of the reasons why the processor
isn't supported.

3.2.3. R4000 and R5000 family

Linux supports many of the members of the R4000 family. Currently
these are R4000PC, R4400PC, R4300, R4600, R4700, R5000, R5230, R5260.
Many others are probably working as well.

Not supported are R4000MC and R4400MC CPUs (that is multiprocessor
systems) as well as R5000 systems with a CPU controlled second level
cache. This means where the cache is controlled by the R5000 itself
in contrast to some external external cache controller. The
difference is important because, unlike other systems, especially PCs,
on MIPS the cache is architecturally visible and needs to be
controlled by software.

Special credit goes to Ulf Carlsson ([email protected]) who provided
the CPU module for debugging the R4000SC / R4400SC support.

3.2.4. R8000

The R8000 is currently unsupported partly because this processor is
relatively rare and has only been used in a few SGI machines, partly
because the Linux/MIPS developers don't have such a machine.

The R8000 is a pretty interesting piece of silicon. Unlike the other
members of the MIPS family it is a set of seven chips. It's cache and
TLB architecture are pretty different from the other members of the
MIPS family. It was born as a quick hack to get the floating point
crown back to Silicon Graphics before the R10000 is finished.

3.2.5. R10000

The R10000 is supported as part of the mips64 kernel which currently
is supported on the IP22 (SGI Indy, Challenge S and Indigo 2) and
Origin.

Due to the very hard to handle way this processor works in non-
cachecoherent systems it's probably still taking some time until we
support this processor in such systems. As of today these systems are
the SGI O2 and Indigo

3.3. Hardware we're never going to support

3.3.1. IBM RS6000

As the name say these are IBM machines which are based on the RS6000
processor series and as such they're not subject of the Linux/MIPS
project. People frequently confuse the IBM RS6000 with the MIPS R6000
architecture. However the Linux/PPC project might do so. Checkout
<http://www.linuxppc.org/> for further information.

3.3.2. VaxStation

As the name already implies this machine is a member of Digital
Equipment's VAX family. It's mentioned here because people often
confuse it with Digital's MIPS based DECstation family due to the
similar type numbers. These two families of architectures share little
technical similarities. Unfortunately the VaxStation, like the entire
VAX family, is currently unsupported.

3.3.3. SGI VisPC

This is actually an x86 based system, therefore not covered by this
FAQ. But to make your search for answers simple, here it is. Ken
Klingman ([email protected]) posted on January 17, 1999 to SGI's
Linux mailing list:

We are working on it. We're actually close to getting
the base level system support into the 2.2 release.
Software-only X and OpenGL should follow relatively
shortly, but hardware-accelerated OpenGL is still
some time off. See www.precisioninsight.com for
news about hardware-accelerated OpenGL.

For more information see the Documentation/ of Linux kernel versions
from 2.2.0 and newer. There is additional information available on
the web on <http://oss.sgi.com/>. Note that the SGI/MIPS and
SGI/Intel people are working independently of each other, therefore
the sources in the anonymous CVS on oss.sgi.com may or may not work
for Intel machines; we don't test this.

3.3.4. Motorola 68k based machines like the Iris 3000

These are very old machines, probably more than ten years old by now.
As these machines are not based on MIPS processors this document is
the wrong place to search for information. However, in order to make
things easy, these machines are currently not supported.

4. Linux distributions.

4.1. RedHat

For MIPSeb, there's Rough Cuts Linux, previously known as Hard Hat
Linux, which is most of Red Hat Linux 5.1 ported for MIPSeb. You can
get this at <ftp://oss.sgi.com/pub/hardhat>.

It is also bundled along with M68k, UltraSparc and PowerPC in a
package called "Rough Cuts" pressed by Red Hat, and available wherever
Red Hat products are sold. This is a very convenient way to get it
without having to download 280MB. You can order Rough Cuts directly
from Red Hat at <http://www.redhat.com/product.phtml/RC1000>.

As well, there's a distribution based on Red Hat 5.2 that's targetting
the Cobalt Qubes; those binaries will work perfectly on other MIPSel
architectures available at <ftp://intel.cleveland.lug.net/pub/Mipsel>.
<ftp://bolug.uni-bonn.de/mips> has various rpm packages from
Redhat 6.0 and 6.1.

4.2. Debian

A Debian port is underway. Current efforts are being bootstrapped
using SGI/Linux as a base, and dpkg compiles natively with few
changes. In addition to the SGI version, some interest has been shown
in little endian platforms. Keep an eye on the Debian-MIPS Port page,
<http://www.debian.org/ports/mips/> for developments.

5. Linux/MIPS net resources.

5.1. Anonymous FTP servers.

The two primary anonymous FTP servers for Linux/MIPS are

oss.sgi.com
This server should satisfy almost all your Linux/MIPS related
ftp desires. Really.

ftp.fnet.fr
This server is currently pretty outdated; it's included here
mostly for completeness and for people with interest in
prehistoric software.

On all these ftp servers there is a list of mirror sites you may want
to use for faster access.

Another source for little endian MIPS binaries is
ftp://intel.cleveland.lug.net/pub/Mipsel which carries mostly newer
versions of binaries for the Redhat flavour shipping with the
Cobalt's.

5.2. Anonymous CVS servers.

For those who always want to stay on the bleeding edge and want to
avoid having to download patch files or full tarballs we also have an
anonymous CVS server. Using CVS you can checkout the Linux/MIPS
source tree with the following commands:

cvs -d :pserver:[email protected]:/cvs login
(Only needed the first time you use anonymous CVS, the password is "cvs")
cvs -d :pserver:[email protected]:/cvs co <repository>

where you insert linux, libc, gdb or faq for <repository>.

The other important CVS archive of the Linux community is
vger.rutgers.edu where a lot of code is being collected before being
sent to Linus for distribution. Although vger itself no longer offers
anonymous access, there are mirror sites which do provide anonymous
access. For details how to access them see
<http://cvs.on.openprojects.net/>. The modules which are of interest
are ``linux'', ``modutils'', ``pciutils'', ``netutils''.

5.3. Web servers.

The two primary web servers for Linux/MIPS are

<http://oss.sgi.com/mips>
This server covers most of Linux/MIPS; it's somewhat SGI centric
but since Linux/MIPS tries to be the same on every platform most
of its information is of interest to all users.

<http://lena.fnet.fr>
This server is currently pretty outdated; it's included here
mostly for completeness.

All these servers have mirrors scattered all over the world; you may
want to use one for best performance.

5.4. Web CVS server.

Via <http://oss.sgi.com/mips/cvsweb> you have directs access the new
Linux/MIPS kernel sources and a few other projects hosted in the same
CVS archive. The intuitive interface allows you to follow the
development at the click of your mouse.

5.5. Mailing lists.

There are three Linux/MIPS oriented mailing lists:

[email protected]
This mailing list is used for most non-SGI related communication
of all kinds. Subscription is handled by a human; send your
subscription requests to [email protected]. You can
unsubscribe from this mailing list by sending unsubscribe <your-
email-address> to the same address.

[email protected]
This mailing list currently has the most traffic. It's somewhat
SGI-centric but is nevertheless of interest especially to
developers as a good number of SGI engineers are subscribed to
this list. Subscription to this list is handled via Majordomo
([email protected]); just send an email with the words
subscribe linux. In order to unsubscribe send unsubscribe
linux. Note that you have to be subscribed if you want to post;
the growth of spam forced us into that policy. For more
information see also <http://oss.sgi.com/mips/email.html>.

[email protected]
This mailing list has only very low traffic as most people tend
to use one of the above mailing lists. Subscription is handled
via Majordomo ([email protected]); just send an email
with the words subscribe linux-mips. In order to unsubscribe
send unsubscribe linux-mips.

5.6. IRC channel.

There is a IRC channel named #mipslinux for Linux/MIPS which may be
found on irc.openprojects.net.

6. Installation of Linux/MIPS and common problems.

6.1. NFS booting fails.

Usually the reason for this is that people have unpacked the tar
archive under IRIX, not Linux. Since the representation of device
files over NFS is not standardized between various Unices, this fails.
The symptom is that the system dies with the error message ``Warning:
unable to open an initial console.'' right after mounting the NFS
filesystem.

For now the workaround is to use a Linux system (doesn't need to be
MIPS) to unpack the installation archive onto the NFS server. The NFS
server itself may be any type of UNIX.

6.2. Self compiled kernels crash when booting.

When I build my own kernel, it crashes. On an Indy the crash message
looks like the following; the same problem hits other machines as well
but may look completely different.

Exception: <vector=UTLB Miss>
Status register: 0x300004803<CU1,CU0,IM4,IPL=???,MODE=KERNEL,EXL,IE>
Cause register: 0x8008<CE=0,IP8,EXC=RMISS>
Exception PC: 0x881385cc, Exception RA: 0x88002614
exception, bad address: 0x47c4
Local I/O interrupt register 1: 0x80 <VR/GIO2>
Saved user regs in hex (&gpda 0xa8740e48, &_regs 0xa8741048):
arg: 7 8bfff938 8bfffc4d 880025dc
tmp: 8818c14c 8818c14c 10 881510c4 14 8bfad9e0 0 48
sve: 8bfdf3e8 8bfffc40 8bfb2720 8bfff938 a8747420 9fc56394 0 9fc56394
t8 48 t9 8bfffee66 at 1 v0 0 v1 8bfff890 k1 bad11bad
gp 881dfd90 fp 9fc4be88 sp 8bfff8b8 ra 88002614

PANIC: Unexpected exception

This problem is caused by a still unfixed bug in Binutils newer than
version 2.7. As a workaround, change the following line in
arch/mips/Makefile from:

LINKFLAGS = -static -N

to:

LINKFLAGS = -static

6.3. Booting the kernel on the Indy fails with PROM error messages

>> boot bootp()/vmlinux
73264+592+11520+331680+27848d+3628+5792 entry: 0x8df9a960
Setting $netaddres to 192.168.1.5 (from server deadmoon)
Obtaining /vmlinux from server deadmoon

Cannot load bootp()/vmlinux
Illegal f_magic number 0x7f45, expected MIPSELMAGIC or MIPSEBMAGIC.

This problem only happens for Indys with very old PROM versions which
cannot handle the ELF binary format which Linux uses. A solution for
this problem is in the works.

6.4. Where can I get the little endian firmware for my SNI?

SNI's system can be operated in both big and little endian modes. At
this time Linux/MIPS only supports the little endian firmware. This
is somewhat unlucky since SNI hasn't shipped that firmware for quite
some time, since they dropped NT.

When running in big endian mode the firmware looks similar to an SGI
Indy which is already supported, therefore fixing the SNI support will
be relativly easy. Interested hackers should contact Ralf B�chle
([email protected]).

6.5. ld dies with signal 6

collect2: ld terminated with signal 6 [Aborted]

This is a known bug in older binutils versions. You will have to
upgrade to binutils 2.8.1 plus very current patches.

6.6. My machine doesn't download the kernel when I try to netboot

Your machine is replying to the BOOTP packets (you may verify this
using a packet sniffer like tcpdump or ethereal) but doesn't download
the kernel from your BOOTP server. This is happens if your boot server
is running a kernel of the 2.3 series or higher. The problem may be
circumvented by doing a "echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc"
as root on your boot server.

6.7. Bug in DHCP version 2

When using DHCP version 2 you might see the following problem: Your
machines receives it's BOOTP reply 3 times but refuses to start TFTP.
You can fix this by doing a "unsetenv netaddr" in the PROM command
monitor before you boot your system. DHCP version 3 fixes that
problem.

7. Milo

Milo is the boot loader used to boot the little endian MIPS systems
with ARC firmware, currently the Jazz family and the SNI RM 200.
While Milo uses the same name and has a similar purpose to the Alpha
version of Milo, these two Milos have nothing else in common. They
were developed by different people, don't share any code, and work on
different hardware platforms. The fact that both have the same name
is just a kind of historic ``accident''.

Plans are to remove the need for Milo in the near future.

7.1. Building Milo

The building procedure of Milo is described in detail in the README
files in the Milo package. Since Milo has some dependencies to kernel
header files which have changed over time Milo often cannot be built
easily; however the Milo distribution includes binaries for both Milo
and Pandora.

7.2. Pandora

Pandora is a simple debugger. It has been primarily developed in
order to analyze undocumented systems. Pandora includes a
dissassembler, memory dump functions and more. If you only want to
use Linux there is no need to install Pandora. It's small though.

8. Loadable Modules

Using modules on Linux/MIPS is quite easy; it should work as expected
for people who have used it on other Linux systems. If you want to
run a module-based system then you should have at least kernel version
980919 and modutils newer than version 2.1.121 installed. Older
versions won't work.

9. How do I setup a crosscompiler?

9.1. Available binaries

The easist thing to setup a crosscompiler is to just download the
binaries. For Linux/i386 hosts and big endian targets this are the
packages:

binutils-mips-linux-2.8.1-1.i386.rpm
egcs-c++-mips-linux-1.0.3a-1.i386.rpm
egcs-g77-mips-linux-1.0.3a-1.i386.rpm
egcs-libstdc++-mips-linux-2.8.0-1.i386.rpm
egcs-mips-linux-1.0.3a-1.i386.rpm
egcs-objc-mips-linux-1.0.3a-1.i386.rpm

And this is the list of packages for little endian targets:

binutils-mipsel-linux-2.8.1-1.i386.rpm
egcs-c++-mipsel-linux-1.0.3a-1.i386.rpm
egcs-g77-mipsel-linux-1.0.3a-1.i386.rpm
egcs-libstdc++-mipsel-linux-2.8.0-1.i386.rpm
egcs-mipsel-linux-1.0.3a-1.i386.rpm
egcs-objc-mipsel-linux-1.0.3a-1.i386.rpm

It's not necessary that you install all these packages; most people
can just omit the C++, Objective C and Fortran 77 compilers. The
Intel binaries have been linked against GNU libc 2.1, so you may have
to install that as well when upgrading.

9.2. Building your own crosscompiler

First of all go and download the following source packages and
patches:

� binutils-2.8.1.tar.gz

� binutils-2.8.1-2.diff.gz

� egcs-1.0.3a.tar.gz

� egcs-1.0.3a-1.diff.gz

� glibc-2.0.6.tar.gz

� glibc-crypt-2.0.6.tar.gz

� glibc-localedata-2.0.6.tar.gz

� glibc-linuxthreads-2.0.6.tar.gz

These are the currently recommended versions. Older versions may
or may not be working. If you're trying to use older versions
please don't send bug reports; we don't care. When installing
please install things in the order binutils, egcs, then glibc.
Unless you have older versions already installed, changing the
order will fail. The installation description below mentions a
number of patches which you can get from the respective SRPM
packages on oss.sgi.com. However since these SRPM packages are
intended to be compiled natively it's not possible to just rebuild
them.

9.3. Diskspace requirements

For the installation you'll have to choose a directory for
installation. I'll refer to that directory below with <prefix>. To
avoid a certain problem it's best to use the same value for <prefix>
as your native gcc. For example if your gcc is installed in
/usr/bin/gcc then choose /usr for <prefix>. You must use the same
<prefix> value for all the packages that you're going to install.

During compilation you'll need about 31mb diskspace for binutils; for
installation you'll need 7mb diskspace for on <prefix>'s partition.
Building egcs requires 71mb and installation 14mb. GNU libc requires
149mb diskspace during compilation and 33mb for installation. Note
these numbers are just a guideline and may differ significantly for
different processor and operating system architectures.

9.4. Byte order

One of the special features of the MIPS architecture is that all
processors except the R8000 can be configured to run either in big or
in little endian mode. Byte order means the way the processor stores
multibyte numbers in memory. Big endian machines store the byte with
the highest value digits at the lowest address while little endian
machines store it at the highest address. Think of it as writing
multi-digit numbers from left to right or vice versa.

In order to setup your crosscompiler correctly you have to know the
byte order of the crosscompiler target. If you don't already know,
check the section ``Hardware Platforms'' for your machine's byteorder.

9.5. Configuration names

Many of the packages based on autoconf support many different
architectures and operating systems. In order to differentiate
between these many configurations, names are constructed with
<cpu>-<company>-<os> or even <cpu>-<company>-<kernel>-<os>. Expressed
this way the configuration names of Linux/MIPS are mips-unknown-linux-
gnu for big endian targets or mipsel-unknown-linux-gnu for little
endian targets. These names are a bit long and are allowed to be
abbreviated to mips-linux or mipsel-linux. You must use the same
configuration name for all packages that comprise your
crosscompilation environment. Also, while other names like mips-sni-
linux or mipsel-sni-linux are legal configuration names, use mips-
linux or mipsel-linux instead; these are the configuration names known
to other packages like the Linux kernel sources and they'd otherwise
have to be changed for crosscompilation.

I'll refer to the target configuration name below with <target>.

9.6. Installation of GNU Binutils.

This is the first and simplest part - at least as long as you're
trying to install on any halfway-sane UNIX flavour. Just cd into a
directory with enough free space and do the following:

gzip -cd binutils-<version>.tar.gz | tar xf -
cd binutils-<version>
patch -p1 < ../binutils-<version>-mips.patch
./configure --prefix=<prefix> --target=<target>
make CFLAGS=-O2
make install

This usually works very easily. On certain machines using GCC 2.7.x
as compiler is known to dump core. This is a known bug in GCC and can
be fixed by upgrading to GCC 2.8.1 or egcs.

9.7. Assert.h

Some people have an old assert.h headerfile installed, probably a
leftover from an old crosscompiler installation. This file may cause
autoconf scripts to fail silently; it was never necessary and was only
installed because of a bug in older GCC versions. Check to see if the
file <prefix>/<target>/include/assert.h exists in your installation.
If so, just delete the it: it should never have been installed for any
version of the crosscompiler and will cause trouble.

9.8. Installing the kernel sources

Installing the kernel sources is simple. Just place them into some
directory of your choice and configure them. Configuring them is
necessary such that files which are generated by the procedure will be
installed. Make shure you enable CONFIG_CROSSCOMPILE near the end of
the configuration process. The only problem you may run into is that
you may need to install some required GNU programs like bash or have
to override the manufacturer-provided versions of programs by placing
the GNU versions earlier in the PATH variable. Now go to the
directory <prefix>/<target>/include and create two symbolic links
named asm and linux pointing to include/asm rsp. include/linux within
your just installed and configured kernel sources. These are
necessary such that necessary header files will be found during the
next step.

9.9. First installation of egcs

Now the not-so-funny part begins: there is a so-called bootstrap
problem. In our case that means the installation process of egcs
needs an already- installed glibc, but we cannot compile glibc because
we don't have a working crosscompiler yet. Luckily you'll only have
to go through this once when you install a crosscompiler for the first
time. Later when you already have glibc installed things will be much
smoother. So now do:

gzip -cd egcs-1.0.3a.tar.gz | tar xf -
cd egcs-<version>
patch -p1 < ../egcs-1.0.3a-mips.patch
./configure --prefix=<prefix> --with-newlib --target=<target>
make SUBDIRS="libiberty texinfo gcc" ALL_TARGET_MODULES= \
CONFIGURE_TARGET_MODULES= INSTALL_TARGET_MODULES= LANGUAGES="c"

Note that we deliberately don't build gcov, protoize, unprotoize and
the libraries. Gcov doesn't make sense in a crosscompiler environment
and protoize and unprotoize might even overwrite your native programs
- this is a bug in the gcc makefiles. Finally we cannot build the
libraries because we don't have glibc installed yet. If everything
went successfully, install with:

make SUBDIRS="libiberty texinfo gcc" INSTALL_TARGET_MODULES= \
LANGUAGES="c" install

If you only want the crosscompiler for building the kernel, you're
done. Crosscompiling libc is only required to be able to compile user
applications.

9.10. Test what you've done so far

Just to make shure that what you've done so far is actually working
you may now try to compile the kernel. Cd to the MIPS kernel's
sources and type ``make clean; make dep; make''. If everything went
ok do ``make clean'' once more to clean the sources.

9.11. Installing GNU libc

Do:

gzip -cd glibc-2.0.6.tar.gz | tar xf -
cd glibc-2.0.6
gzip -cd glibc-crypt-2.0.6.tar.gz | tar xf -
gzip -cd glibc-localedata-2.0.6.tar.gz | tar xf -
gzip -cd glibc-linuxthreads-2.0.6.tar.gz | tar xf -
patch -p1 < ../glibc-2.0.6-mips.patch
mkdir build
cd build
CC=<target>-gcc BUILD_CC=gcc AR=<target>-ar RANLIB=<target>-ranlib \
../configure --prefix=/usr --host=<target> \
--enable-add-ons=crypt,linuxthreads,localedata --enable-profile
make

You now have a compiled GNU libc which still needs to be installed.
Do not just type make install. That would overwrite your host sys�
tem's files with Linux/MIPS-specific files with disastrous effects.
Instead install GNU libc into some other arbitrary directory <somedir>
from which we'll move the parts we need for crosscompilation into the
actual target directory:

make install_root=<somedir> install

Now cd into <somedir> and finally install GNU libc manually:

cd usr/include
find . -print | cpio -pumd <prefix>/<target>/include
cd ../../lib
find . -print | cpio -pumd <prefix>/<target>/lib
cd ../usr/lib
find . -print | cpio -pumd <prefix>/<target>/lib

GNU libc also contains extensive online documentation. Your systems
might already have a version of this documentation installed, so if
you don't want to install the info pages, which will save you a less
than a megabyte, or already have them installed, skip the next step:

cd ../info
gzip -9 *.info*
find . -name \*.info\* -print | cpio -pumd <prefix>/info

If you're not bootstrapping your installation is now finished.

9.12. Building egcs again

The first attempt of building egcs was stopped by lack of a GNU libc.
Since we now have libc installed we can rebuild egcs but this time as
complete as a crosscompiler installation can be:

gzip -cd egcs-<version>.tar.gz | tar xf -
cd egcs-<version>
patch -p1 < ../egcs-1.0.3a-mips.patch
./configure --prefix=<prefix> --target=<target>
make LANGUAGES="c c++ objective-c f77"

As you can see the procedure is the same as the first time with the
exception that we dropped the --with-newlib option. This option was
necessary to avoid the libgcc build breaking due to the lack of libc.
Now install with:

make LANGUAGES="c c++ objective-c f77" install

You're almost finished. If you think you don't need the Objective C
or F77 compilers you can omit them from above commands; each will save
you about 3mb. Do not build gcov, protoize or unprotoize.

9.13. Should I build the C++, Objective C or F77 compilers?

The answer to this question largely depends on your use of your
crosscompiler environment. If you only intend to rebuild the Linux
kernel then you have no need for the full blown setup and can safely
omit the Objective C and F77 compilers. You must, however, build the
C++ compiler, because building the libraries included with the egcs
distribution requires C++.

9.14. Known problem when crosscompiling

9.14.1. IRIX crashes

Origin 200 running IRIX 6.5.1 may crash when running ``make depend''
on the Linux kernel sources. IRIX 6.5 on Indy and IRIX 6.5.4 on
Origin 200 are known to work. Further reports on that help isulating
the problematic configuration are welcome.

9.14.2. Resource limits on System V based hosts

Typical System V based Unices like IRIX or Solaris have limits for the
maximum number of arguments to be passed to a child process which may
be exceeded when crosscompiling some software like the Linux kernel or
GNU libc. For IRIX systems the maximum length of the argument list
defaults to 20kb while Linux defaults to at least 128kb. This size
can be modified by the command ``systune ncargs 131072'' as root.

9.15. GDB

Building GDB as crossdebugger is only of interest to kernel
developers; for them GDB may be a life saver. Such a remote debugging
setup always consists of two parts: the remote debugger GDB running
on one machine and the target machine running the Linux/MIPS kernel
being debugged. The machines are typically interconnected with a
serial line. The target machine's kernel needs to be equipped with a
``debugging stub'' which communicates with the GDB host machine using
the remote serial protocol.

Depending on the target's architecture you may have to implement the
debugging stub yourself. In general you'll only have to write very
simple routines for serial. The task is further simplified by the
fact that most machines are using similar serial hardware typically
based on the 8250, 16450 or derivatives.

10. Related Literature

10.1. See MIPS Run

author Dominic Sweetman, published Morgan Kaufmann, ISBN
1-55860-410-3.

This is intended as a pretty comprehensive guide to programming MIPS,
wherever it's different from programming any other 32-bit CPU. It's
the first time anyone tried to write a readable and comprehensive
explanation and account of the wide range of MIPS CPUs available, and
should be very helpful for anyone programming MIPS who isn't insulated
by someone else's operating system. And the author is a free-unix
enthusiast who subscribes to the Linux/MIPS mailing list!

John Hennessey, father of the MIPS architecture, was kind enough to
write in the foreword: ``... this book is the best combination of
completeness and readability of any book on the MIPS architecture
...'';

It includes some context about RISC CPUs, a description of the
architecture and instruction set including the "co-processor 0"
instructions used for CPU control; sections on caches, exceptions,
memory management and floating point. There's a detailed assembly
language guide, some stuff about porting, and some fairly heavy-duty
software examples.

Available from:

� <http://www.algor.co.uk/algor/info/seemipsrun.html> (europe)

� <http://www.mkp.com/books_catalog/1-55860-410-3.asp> (US)

and from good bookshops anywhere. It's 512 pages and costs around $50
in the US, �39.95 in the UK.

I'd be inclined to list two other books too, both from Morgan Kaufmann
and available from www.mkp.com or any good bookshop:

10.2. The MIPS Programmer's Handbook

authors Farquhar and Bunce, published by Morgan Kaufmann,
ISBN 1-55860-297-6.

A readable introduction to the practice of programming MIPS at the low
level, by the author of PMON. Strengths: lots of examples; weakness:
leaves out some big pieces of the architecture (such as memory
management, floating point and advanced caches) because they didn't
feature in the LSI ``embedded''; products this book was meant to
partner.

10.3. Computer Architecture - A Quantitative Approach

authors Hennessy & Patterson, published Morgan Kaufmann,
ISBN 1-55860-329-8.

The bible of modern computer architecture and a must-read if you want
to understand what makes programs run slow or fast. Is it about MIPS?
Well, it's mostly about something very like MIPS... Its sole defect
is its size and weight - but unlike most big books it's worth every
page.

10.4. UNIX System V ABI MIPS Processor Supplement

by Prentice Hall, published 05/1991, ISBN 0-13880-170-3. This book
defines many of the MIPS specific technical standards like calling
conventions, ELF properties and much more that are being used by
Linux/MIPS. Unfortunately it's out of print. Similarly the site
"http://www.mipsabi.org/" is offline.