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Re: [avr-gcc-list] a symbol for end of program memory used?
From: |
Erik Christiansen |
Subject: |
Re: [avr-gcc-list] a symbol for end of program memory used? |
Date: |
Thu, 29 Apr 2010 23:18:32 +1000 |
User-agent: |
Mutt/1.5.15+20070412 (2007-04-11) |
On Wed, Apr 28, 2010 at 12:07:18PM -0700, Paul Stoffregen wrote:
> So far, I'm using "__data_load_end" to know where the unused flash memory
> begins. Is that the best way? Does the linker provide any special symbols
> or other way I can get the end of allocated flash memory as a constant
> which I can use in my program?
Looking at the avr linker script which I last used, __data_load_end
seems a suitable choice for your purpose, _if_ you have nothing in
.eeprom. All that follows then is .bss and .noinit, neither of which
produce loadable data.
And given:
.data : AT (ADDR (.text) + SIZEOF (.text))
__data_load_start = LOADADDR(.data);
__data_load_end = __data_load_start + SIZEOF(.data);
it is then an LMA you can use in that case.
But the .eeprom output section specifies an LMA coincident with
__data_load_end. To be safe, I'd place something like the following
after the end of the .eeprom output section in the linker script:
__vacant_flash = __data_load_end + SIZEOF(.eeprom);
or with same effect:
__vacant_flash = LOADADDR(.eeprom) + SIZEOF(.eeprom);
That should just about do it.
(Caveat: Untested; And the hour is late here.)
Better still, would be to use a custom linker script to manage location
of your extra stuff which goes into flash, by adding your own section.
(Oh, all right, that's a little bit more effort.)
Erik
--
Crime does not pay ... as well as politics.
-- A. E. Newman