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Re: Harvard architecture MLT files
- From: Andrew Lunn <andrew dot lunn at ascom dot ch>
- To: Robert Cragie <rcc at jennic dot com>
- Cc: ECOS <ecos-discuss at sources dot redhat dot com>
- Date: Wed, 2 Jul 2003 13:37:40 +0200
- Subject: Re: [ECOS] Harvard architecture MLT files
- References: <NMEDLDELHPEFHOMFIJBHCENGCMAA.rcc@jennic.com>
On Wed, Jul 02, 2003 at 12:00:30PM +0100, Robert Cragie wrote:
> I have an implementation of the OpenRISC core which is pure Harvard, i.e. no
> caches/mmus, separate instruction bus and memory, separate data bus and
> memory.
Does gcc know the processor is a true Harvard? We built our own custom
DSP which was a true Harvard and someone did a quick and dirty gcc
port to it. Unfortunately the gcc port did not know it was a Harvard
and kept putting constants in the code section assuming it could
access them like the data section.
> 1) How do I now layout the MLT files? It's no longer ROM and RAM, it's more
> like ROM(inst), ROM(data), RAM(data). Here is a stab at the .ldi file:
>
> // eCos memory layout
>
> #include <cyg/infra/cyg_type.inc>
>
> MEMORY
> {
> inst : ORIGIN = 0x00000000, LENGTH = 0x00020000
> data : ORIGIN = 0x01000000, LENGTH = 0x00020000
> }
>
> SECTIONS
> {
> SECTIONS_BEGIN
> SECTION_vectors (inst, 0x00000100, LMA_EQ_VMA)
On the ARM, fixed_vectors is actually data. No idea about the
OpenRisc.
Andrew
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