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Re: ROM and hardware vectors for ARM.
- From: Gary Thomas <gthomas at ecoscentric dot com>
- To: Erik Aagaard Knudsen <EAK at penell dot com>
- Cc: "'ecos-discuss at sources dot redhat dot com'" <ecos-discuss at sources dot redhat dot com>
- Date: 17 Oct 2002 08:18:37 -0600
- Subject: Re: [ECOS] ROM and hardware vectors for ARM.
- References: <AB439ADBB821D41181CC00D0B7458AEB01B62F98@SRV-EXCHANGE>
On Thu, 2002-10-17 at 08:12, Erik Aagaard Knudsen wrote:
> It is our inpression that in order to be able to debug an application on an
> ARM-target, the ROM-redboot must
>
> 1. Boot from adr 0x0 and initialize the CPU/Memory
> 2. Remap the system so that the boot ROM is removed from addr. 0x0 and
> replaced by RAM.
> 3. Interrupt vectors is then initialized in this new RAM at addr. 0x0
>
> What can we do if we do not have the possibility of remapping (swapping
> ROM/RAM addresses)?
Why can't you? What's your processor (core)?
>
> The secondary vector table is located in the vectors section ( 0x20 up). Can
This would take some work. The vectors assume that the secondary table
can be reached with a PC-relative instruction, which limits how far away
the table can be - probably out of reach if it's in a different section
of memory.
> this table without too much fuss be moved to RAM instead (f.ex. into the
> fixed vectors section)? This would ofcourse mean that we have to initialize
> these RAM locations with the correct pointers, but it would mean that these
> vector pointers could be located anywhere in the memory space, hense
> removing the need for hardware remapping logic.
>
> Are there other problems, which we have not identified?
>
Yes, plenty of them. Grant Edwards did this a long time ago,
he might be able to give some insight.
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Gary Thomas |
eCosCentric, Ltd. |
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