[ECOS] ARM - RAM region at other address than 0

Gary D. Thomas gary.thomas@mind.be
Mon May 19 20:51:00 GMT 2003

On Mon, 2003-05-19 at 14:33, Grant Edwards wrote:
> On Mon, May 19, 2003 at 04:11:38PM -0400, Doyle, Patrick wrote:
> > I glanced at the '5471 data manual and I don't see the
> > "mechanism for swapping ROM and SDRAM at address 0" that I was
> > expecting to see... Hmmm.... Perhaps you should ask TI about
> > this.  eCos really likes to see interrupt vectors in RAM.
> At one point I had a hacked version of vectors.S that worked
> with ROM at 0.  It did the "double vector" thing (not very
> pretty).  After tiring of the requirement to maintain my own
> vectors.S, I finally swapped ROM/RAM -- life is easier that
> way.
> If the 5471 doesn't have some sort of software-controlled
> chip-select logic, then when you lay out your board you should
> add a couple gates to allow two of the chip selects to be
> swapped.

I personally think that using hardware to swap these segments is
the correct solution.  However, if anyone wants to experiment 
with Grant's approach (from *long* ago), I still have the patches
that he sent me for this :-)

Gary D. Thomas <gary.thomas@mind.be>

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