Subject: Re: Advice on adding support for a new Platform
To: Chris Gilbert <>
From: Ben Harris <>
List: port-arm
Date: 06/07/2001 00:38:00
On Thu, 7 Jun 2001, Chris Gilbert wrote:

> On Wednesday 06 June 2001  9:06 pm, Thomas J. Merritt wrote:
> > I interested in porting NetBSD/ARM to a platform based upon the Cirrus
> > Logic EP7312.  The EP7312 has an ARM 720T core plus a bunch of peripherals
> > and is similar to the EP7209.  The board is running OpenFirmware.
> > OpenFirmware is able to net load the kernel as an ELF image.  I would
> > appreciate any advice on how to attack the port.
> I presume that the 720T is a thumb based chipset (not looked for the spec on
> it yet)  So certainly an issue is that we currently don't have support for
> thumb in NetBSD (not sure if gcc can do Thumb either).  If it's not Thumb, it
> maybe a matter of adding the checks for it's CPU ID and with a bit of luck
> it'll look enough like an ARM7 core that we'll work with it :)

It's basically a 710T with the fast context switch extension, so John
Fremlin's 7TDMI code should provide all the necessary CPU support.

> Doing an ELF kernel shouldn't be too bad as I believe that arm26 is an ELF
> kernel, so we do have ELF arm stuff around, however we're still not that
> close to doing full blown ELF on arm32, it would probably take some kind of
> cross compiler for the kernel. And some of the asm files would need a bit of
> work to cope with ELF.

They _should_ all be correct.  Certainly it's possible to compile
NetBSD/arm32 ELF kernels, and BtNetBSD should be able to boot them.
Reinoud vanished before he tested my last round of fixes though.

Ben Harris                                                   <>
Portmaster, NetBSD/arm26               <URL:>