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Re: RAM Images on AT91SAM7s256
- From: Andrew Lunn <andrew at lunn dot ch>
- To: "Alois Z." <alois at gmx dot at>
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Mon, 28 Jan 2008 17:46:54 +0100
- Subject: Re: [ECOS] RAM Images on AT91SAM7s256
- References: <20080128160738.64350@gmx.net>
On Mon, Jan 28, 2008 at 05:07:38PM +0100, Alois Z. wrote:
> Hi,
>
> I currently working with a AT91SAM7s256 based board. For debugging
> and testing I like to devlop RAM only images.
With only 64Kbytes of RAM, you will be very limited to what you can
do. I strongly suggest you get a JTAG debugger which can set hardware
breakpoints. You can then run your application from ROM and single
step, set a couple of breakpoints etc.
> As the existing eCos
> support for this platform has only definitions for rom images I
> tried to use the existing files for ram linker file
> definitions. After looking through several ldi files and googling
> around I'm not quite shure if made the right placement for the
> 'SECTION_rom_vectors' and the 'SECTION_fixed_vectors' sections.
>
> Currently my ram.ldi looks like:
>
> MEMORY
> {
> ram : ORIGIN = 0x00200000, LENGTH = 0x10000
> }
>
> SECTIONS
> {
> SECTIONS_BEGIN
> SECTION_rom_vectors (ram, 0x00200000, LMA_EQ_VMA)
> SECTION_fixed_vectors (ram, ALIGN (0x1), LMA_EQ_VMA)
> SECTION_text (ram, ALIGN (0x1), LMA_EQ_VMA)
> SECTION_fini (ram, ALIGN (0x4), LMA_EQ_VMA)
> SECTION_rodata (ram, ALIGN (0x4), LMA_EQ_VMA)
> SECTION_rodata1 (ram, ALIGN (0x4), LMA_EQ_VMA)
> SECTION_fixup (ram, ALIGN (0x4), LMA_EQ_VMA)
> SECTION_gcc_except_table (ram, ALIGN (0x4), LMA_EQ_VMA)
> SECTION_data (ram, ALIGN (0x4), FOLLOWING (.gcc_except_table))
> SECTION_bss (ram, ALIGN (0x4), LMA_EQ_VMA)
> CYG_LABEL_DEFN(__heap1) = ALIGN (0x8);
> SECTIONS_END
> }
This looks reasonable.
How are you going to get this image into RAM?
You also need to make sure that RAM is mapped to address 0x0 as well
as 0x00200000. I know ROM startup does this, but i think RAM startup
probably does not.
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