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Re: moving functions into RAM
- From: Andrew Lunn <andrew at lunn dot ch>
- To: Matt Sartori <msartori at hanoverdisplays dot com>
- Cc: eCos Discussion <ecos-discuss at ecos dot sourceware dot org>
- Date: Mon, 19 Sep 2005 17:59:25 +0200
- Subject: Re: [ECOS] moving functions into RAM
- References: <F9885E669725F248A1F6DB9109FDD67905E510@Molly.hanover.local>
On Mon, Sep 19, 2005 at 01:54:43PM +0100, Matt Sartori wrote:
> Hi all,
> I've looked through all the archived posts that mention the
> Relocation truncated to fit: R_ARM_PC24
> and any mention of
> __attribute__ (section(
>
Take the intel Strata as an example:
int flash_erase_block(volatile flash_t *block, unsigned int block_size)
__attribute__ ((section (".2ram.flash_erase_block")));
int flash_erase_block(volatile flash_t *block, unsigned int block_size)
{
volatile flash_t *ROM;
flash_t stat = 0;
This will cause the code to be placed in ram.
The fact you are getting a relocation error, suggests this is working
for you. Your ROM and RAM are too far apart to be able to make a
branch. You need to make a jump instead. Now the io flash driver code
knowns how to do this properly.
// Use this function to make function pointers anonymous - forcing the
// compiler to use jumps instead of branches when calling driver
// services.
static void* __anonymizer(void* p)
{
return p;
}
and:
_flash_query = (code_fun*) __anonymizer(&flash_query);
HAL_FLASH_CACHES_OFF(d_cache, i_cache);
(*_flash_query)(data);
HAL_FLASH_CACHES_ON(d_cache, i_cache);
But going through the anonymizer the compiler is forced to use a jump
rather than a branch.
Andrew
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