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IP35 is the CPU board in Silicon Graphics Origin 300, Origin 3000, Onyx 3000, Fuel and Tezro systems. It is the successor of the IP27 architecture of Onyx 2, Origin 200 and Origin 2000 and the last MIPS-based server architecture of Silicon Graphics. Its successor is the IA-64-based Altix series.

Linux Support

IP35 is not yet supported by mainline Linux. A port initially targeting only the Origin 350, but since expanded to the Origin 300, Fuel and Tezro has been started. So far the kernel is usable in uniprocessor mode on Origin 350 and Tezro, but requires manual patches to correctly identify the hardware and set the MAC address of Origin 300 and Fuel systems.

Major bits and pieces still to do:

  • Rebooting and powering off the system via the L1 system controller (all systems).
  • Reading the IOC3 hardware type and MAC address from the L1 system controller (Fuel and Origin 300).
  • Unknown (IRQ?) conflict between the SCSI and USB controllers (Origin 300).
  • PCI IRQ routing and sharing generally (all systems).
  • PCI resource allocation, not just identification (all systems).
  • SMP (all systems).
  • PS/2 keyboard and mouse support (Tezro and Origin 350).
  • The FPU is stuck in FR0 mode (limitation of Linux FPU support on R1x000 CPUs generally).
  • There is a possible TLB bug to track down (possibly R1x000 CPUs generally).
  • Booting a system with an uninitialized VPro (Odyssey) graphics card (thus, without an attached keyboard) locks up the Odyssey driver (Fuel and Tezro, possibly Origin 350 with graphics option).
  • IOC4 serial ports (Tezro and Origin 350).
  • IOC4 IDE (ATA) DMA (Tezro and Origin 350).

A plea for hardware

The development effort could be helped by getting more hardware into the hands of developers. If you have Origin or Onyx hardware or parts that you want to get rid of, don't junk it, don't squeeze out the last few bucks from eBay but get it into the hands of a capable hacker! Another slightly mad but interesting option would be made available a virtual or an actual MIPS based data center to do a build farm on which we can target and conduct research, development and tests. Donors will be made publicly noted if they are willing to be so and regular build jobs will be monitored with small publicity for their kindness in a public site.

Hardware documentation

As not expected differently from any large vendor is hard to come by. Aside of negotiating there are several other leads:

  • Reverse engineering. Dubious legality and painful, so least preferable
  • Various IP35 bits hidden in the code for the already supported IP27.
  • Various bits of information from published information such as header files.
  • Manuals from http://techpubs.sgi.com/:
  • The history tree on kernel.org contains support for the Origin 3000's ill-fated IA-64-based evil brother. It is largely based on the same custom chips, so is a source of documentation and semi-working GPL code. The machine never made it to the market and so in changeset c6bacd5010ec2db31aebbac71bc93540f40d2a9d support for it got deleted.

Hardware documentation and patents

While hardware documentation still is not public a number of patents has been filed on technology used by Origins and its descendents - and for once these patents are actually readable. There are 5,915.104[1] and 6,604,161[2]for the BRIDGE ASIC and 6,282,195[3] for the XBOW ASIC.


  1. US Patent 5,915.104 on BRIDGE as PDF
  2. US Patent 6,604,161 on BRIDGE as PDF
  3. US Patent 6,282,195 on XBOW as PDF

See also