The Linux/MIPS FAQ

What is "Linux/MIPS"?

Linux/MIPS is a port of the LINUX Operating System to computers equipped with MIPS processors. Linux/MIPS is based on the latest sources distributed by Linus Torvalds, the author of the original Linux/i386 kernel.

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On what hardware will it run?

Linux/MIPS will run on most ARC (ARC = Advanced Risc Computing) compliant systems equipped with MIPS R4x00 processors. A port to older R2000 and R3000 microprocessors is now in progress. Ports to the following systems are in progress:

In the meantime many other platforms turned out to be good candidates for Linux/MIPS. Although we don't have code for Mips platforms other than the systems listed above, chances are quite good that some of the following systems will be supported in future:

What is this ARC standard?

The ARC standard is a standard that has been created by the ACE consortium some years ago. It defines certain hardware properties and and set of BIOS routines. The kernel is in no way based on the ARC standard; only the bootloader Milo depends from the ARC standard. Unfortunately the ARC stanrdard has lots of disadvantages: In short it is not necessarily a disadvantage if your machine isn't ARC compliant - as soon someone has written a bootloader this might even be an advantage. An example for a Linux/MIPS systems that isn't ARC conformant is the DECstation series.

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What is the current status of Linux/MIPS?

The kernel is quite reliable and supports ext2fs and NFS filesystems. Other filesystems should also be working but are untested. Supported peripherals can be divided up in four groups:

Is Linux/MIPS little or big endian?

At least all of the ports to ARC systems will be little endian. However, it might be necessary to run older Mips systems, such as the Sony News and Mips RC3xxx, in big endian mode. If and how we can provide user code compatibility thru the whole Mips line hasn't been decided yet.

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Is Linux/MIPS a 64 bit OS?

Not yet. This has multiple reasons: Nevertheless Linux/MIPS uses the advantages of 64 bit register for best possible performance on the 64 bit CPUs of the R-family. To top

Will it run on Multiprocessor machines?

The current kernel doesn't contain very much of the special SMP stuff that is required. It will therefore only make use of one processor. Nevertheless there is
SMP support for Linux/i386.

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What is the state of the project?

We have a bootstrap loader which should run on most ARC systems. A network bootloader for DECstations using the MOP protocol is almost complete.
The current kernels based on Linux 1.3.62 include drivers for console, keyboard and ethernet. SCSI will be available soon. On the Acer, Olivetti and Mips boxes, the kernel boots from a floppy, and then mounts root from a NFS server. The kernel is quite reliable; my own machine has currently an uptime of over five days. The only thing that will prevent it from running longer is the fact that kernel hackers frequently reboot their machines. The IDE-CD driver is working and Linux/MIPS does NFS serving.

A network bootloader for R3000-based DECStations using the MOP protocol is almost complete, though certain models of DECStation may be booted using tftp/bootp. Both R3000 and DECStation specific code has been written for the 1.2.11 kernel, and will be released as patches to the current 1.3.57 kernel soon. An experimental DECStation kernel image is already available. This ought to boot to the point of showing the "Calibrating delay loop..." message on most DECStations based on R3000 CPU's.

On the Linux/MIPS FTP sites is a better than nothing distribution available. It currently just a bunch of thrown-together programs and will somewhen later be replaced by a real distribution.

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Any support/development tools available?

Yes. We have cross compilers, assemblers and linkers ready to use for Linux/i386, SunOS 4.1.3 and Solaris 2.5. A Mips R2000/R3000 simulator (SPIM) for Linux/i386 is also ready to download. Binaries and documentation are available from the Linux/MIPS FTP sites. The current version are gcc 2.7.2 and binutils 2.7. There are patches required to both of these packages in the "src" subdirectory in the above locations. Both GCC and Binutils may be configured in two target flavours: The a.out support has finally been removed from the Linux/MIPS tools.

For ease of installation binaries for Linux/i386 hosts are also available. Native binaries for Linux/MIPS are included in root-0.01.tar.gz and a number of binary packages. Note that the root-0.01.tar.gz packages is a bit outdated but it will get you started.

Linux/MIPS FTP sites

This is a very incomplete list of Linux/MIPS sites. There are more available and you should try always to use the nearest site.

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What Literature about MIPS CPUs is available?

The book MIPS RISC Architecture from Gerry Kane is something like a bible for MIPS programmers. It covers all CPUs upto the R4000 family. The book also contains much other usefull information like the MIPS calling sequence, a list of macro instructions that expand into multiple machine instructions, examples of multiprecission arithmetic and more: There is some additional CPU specific literature about available as Postscript file on SGI's FTP Server. These books contain much more details about the instruction set and hardware but don't cover software aspects very good. Another advantage is of course that these files free.

Also available from SGI on www.sgi.com are

Both books are available online as HTML, for download as Postscript file and for order as printed manual. Some parts are a bit SGI specific but though both manuals like some others from this server provide lots of usefull information usefull for Linux/MIPS hackers.

Is there a mailing list?

Yes, there is a mailing list for developers only. Please send mail to linux-mips@fnet.fr for further information.

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Why should you use Linux/MIPS?

Just a few of the reasons that come to mind:

Can I help?

Sure! If you have a Mips box, please let us know. Eventually we find a way to include your box in the target list. And we would of course appreciate it, if you can spend some time into hacking kernel and/or user code. Please feel free to contact us at

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What does it cost?

Nothing, since Linux/MIPS is freely available. But the development costs -- as any development. We would appreciate any donations such as:

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Last changed 10-Jun-1996 Ralf Bächle Email
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