[geeks] Home made SGI O2 CPU upgrade

[Joshua Boyd]

On Mon, Oct 27, 2003 at 02:45:51PM +0000, Rob Fielding wrote:

> I only wish I know more. I'd love to speed boost my R5 Indy or R10 Octane.
> 
> http://www.nekochan.net/phpBB2/viewtopic.php?t=1071

It won't work in an Octane, nor would we want to do it to an Octane.
You do that to an Octane and you turn the Octane from a 64bit machine to
a 32bit machine.

The procedure as currently performed will never work for an Indy.  The
procedure takes advantage of the fact that the RM5200 CPU is
pin-compatible with the RM7000, I believe both from PMC-Sierra.  The
R5000 chip used in lesser O2s and the Indy are not pin compatible and
they are from NEC (to my recall).  

That means that even for O2 users, you have to have an already fast and
fairly uncommon machine to take advantage of this upgrade.  It may be a
possibility to reverse engineer the RM5200 CPU module enough to make
some, but then there is the issue of firmware.  The upgrade relies on
having the firmware from the RM7000 CPU modules handy, which isn't
something that one is legally able to download and put onto new modules
for sale.  It may be possible to reverse engineer the firmware as well
though... Obviously it bootstraps the CPU, but we still need to have a
general idea of what else it does before handing control to the PROM.
Perhaps if someone in a country that legally allowed it would disasseble
the machine code and post a summary of what it does, someone could write
a knock off?

Anyway, if someone gets all the information together for us to
manufactor our own modules, then we might be able to talk about doing it
to Indys as well, but there would still be the issue of bus speed.  I
doubt an Indy will be able to really take advantage of that much CPU
power.  It would still be cool to do, but it is a tremendous amount of
work for a one off hack.