[ECOS] OpenRISC eCos package

Robert Cragie rcc@jennic.com
Wed Apr 16 10:39:00 GMT 2003


Hi Scott,

I am starting to use the OpenRISC eCos package submitted by you for our
custom target. As we are not using cache or MMU, this has raised some issues
(note I'm not that familiar with the CDL and have some limited experience of
porting, so please bear with me).

1) What's the best way to approach configuration for a 'soft' processor like
this whose architecture can be configured? My thoughts are that you could
either:

a) Include support for everything in the arch and have them selectable via
cdl_packages/cdl_options
b) Properly define variants and platforms and use cdl_interface to indicate
the options variants/platforms export.

(a) seems acceptable for now, but (b) seems to be the 'proper' solution
based on the tenet of configurability promoted by eCos. However, given the
configurability of the OpenRISC CPU, I guess (b) could potentially give you
a large number of combinations - I'm not sure if this would be a problem.

2) Looking at the ARM HAL, cache support is in the platform subdirectory,
whereas for OpenRISC it is in the 'arch' subdirectory. Shouldn't it be in
the platform subdirectory?

3) vectors.S includes cache manipulation code - shouldn't this be elsewhere
(ideally hal_cache.h)?

I'm happy to help sort out the right way to configure eCos for different
options.

Out of interest, what template did you use for the port?

Robert Cragie, Design Engineer
_______________________________________________________________
Jennic Ltd, Furnival Street, Sheffield, S1 4QT,  UK
http://www.jennic.com  Tel: +44 (0) 114 281 2655
_______________________________________________________________


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