In the following, I will describe how to install Debian 7 (wheezy) on SGI O2 (IP32) machines with R5000, R5200 or RM7000 processors.
Note that I will only discuss issues related to the installation on O2 and not go into any details concerning SGI in general. Please read other Debian on SGI HOWTOs, such as this and that document as well as Debian's installation guide for MIPS, before starting. In particular, take a look at Jiann-Ming Su's detailed run-through with the O2 images I've prepared. Once you're familiar with how to set up an environment to load the installer for SGI, you can download the installer image for O2. This image supports installations both via serial console as well as framebuffer.
The installation on O2 is just like on any other platform. Towards the end of the installation, Arcboot will be installed which lets you boot your SGI from disk with the
Thiemo Seufer has done lots of MIPS work on the installer and the kernel. He thoroughly tested the 2.6 kernel on O2 and prepared Debian packages. Also, the debian-installer team has done a great job making an easy-to-use installer which supports many platforms. Finally, I'd also like to thank Jö Fahlke for making an O2 available to me.
If you need any help getting Debian running on your O2 after reading this installation guide and using Google, you can contact the Debian MIPS mailing list.