Subject: Re: Advice on adding support for a new Platform
To: John Fremlin <>
From: Richard Earnshaw <>
List: port-arm
Date: 06/07/2001 22:26:36
> "Thomas J. Merritt" <> writes:
> [...]
> > |It's basically a 710T with the fast context switch extension, so
> > |John Fremlin's 7TDMI code should provide all the necessary CPU
> > |support.
> > 
> > The 720T extends the ARM7TDMI core with an MMU and a few other
> > goodies.
> I'm porting to a 710T, and the so called "7tdmi" code I wrote is for
> the *710T* MMU. As long as the 720T is just a superset of that there
> won't be any hassle until you want to use the extensions . . .

Yep, you should find that, apart from having a different CPU id in CP15 
r0, that the 720T is a strict superset of the 710T (at least from a 
programmer's point of view).


BTW, I think it is probably a mistake to name some of the cpus after the 
basic core name (arm6, arm7, arm8 etc).  Cores don't have MMUs or caches, 
and NetBSD only runs on a core with a MMU.  It would be better to name the 
ports after the full cpu-name (6x0, 710, 710T, 920 etc), then it would be 
clear that the code works for that core+mmu combination.

Take a look at arm/cpufunc{.c,_asm.S} to see what I mean.