[ECOS] ARM port: how to handle ROM at address 0 without MMU ?

heinricg@esiee.fr heinricg@esiee.fr
Mon Feb 16 13:04:00 GMT 2004


-------------------
> >> The thing is I have a platform that has:
> >> - ROM at address 0
> >> - no MMU
> ...
> >> The question is: what do you think is the best way of modifying
the
> >> vectors.S file in order to handle this?
> 
> You will have to move the vectors to ram. For the interrupt vectors,
place the table
> in ram and modify the interrupt support routines in ecos: When a
function registers a
> new interrupt service routine it has to write to the new location in
ram. When the
> interrupt occurs the processor has to fetch the address from the new
location in ram
> (see the chip documentation for this, probably an instruction like
'ldr pc,
> .address_of_memory_location')
> 
> The virtual vector table is used for communication between e.g. the
redboot stub and
> the program you want to debug. I guess you can just move the
location of this table
> to a fixed known location in ram. Compile redboot and compile your
program. As long
> as the location is the same for both, debugging should work.
> 

Thank you Eric,
that corresponds to what I was planning to do. I wanted to make sure I
wasn't going to break anything in the rest of eCOS by doing that.

Cheers,
Gregory Heinrich.

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