Re: [ECOS] Re: ecos bring up on s5pc100(cortex-a8)

[Nick Garnett <nickg at ecoscentric dot com>]

John Dallaway <john@dallaway.org.uk> writes:

> >> The cortexm hal seems like a closer match to me. Although, after
> >> looking at the code, it appears to be very minimal at the moment.

The Cortex-M devices are very different to the A8 and all other
ARMs. Apart from the instruction set, almost all of the architecture
is different. The A8 implements essentially the same architecture as
previous ARMs.

> > eCos runs anything without thumb code and it runs fine here. But if you like to
> > do a cortex-a HAL, I would love to support you. Especially for cortex-a9
> > multicores it will be important.
> 
> Please note that eCos on Cortex-A was discussed some time ago on this
> list in the context of a proposed port to OMAP3530. Ref:
> 
>   http://ecos.sourceware.org/ml/ecos-discuss/2009-05/msg00089.html

Indeed, and the advice given there should remain. The A8 can be viewed
as an ARM9 with some bells and whistles. Most of those bells and
whistles are largely irrelevant to eCos -- they are mainly intended to
make the ARM architecture more suitable for server class applications.
Any A8 port should be based on the ARM architecture HAL, plus an A8
variant HAL and a platform HAL. The A8 variant HAL can be modelled on
the ARM9 variant HAL, and should initially be created by copying it.

-- 
Nick Garnett                                      eCos Kernel Architect
eCosCentric Limited    http://www.eCosCentric.com      The eCos experts
Barnwell House, Barnwell Drive, Cambridge, UK.     Tel: +44 1223 245571
Registered in England and Wales:                        Reg No: 4422071


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