jumping to code in RAM in a MPC55xx
Tehn Yit Chin
tehn.yit.chin at gmail.com
Fri Jul 18 16:29:34 EST 2008
This question is not directly related to linux, but a question on how to
execute code from.
My test code is as follows..
void ram(unsigned int cat) __attribute__ ((section(".ram_code")));
void ram1(void) __attribute__ ((section(".ram_code")));
void flash(void) __attribute__ ((section(".text")));
void flash1(unsigned int y) __attribute__ ((section(".text")));
void ram(unsigned int cat)
unsigned int abc;
abc += 12;
abc += cat;
void flash1(unsigned int y)
unsigned int x;
x = x + y;
unsigned int def;
def += 12;
asm (" bel ram1\n\t");
I have the section .ram_code mapped into the internal SRAM of the MPC55xx,
which starts at 0x40000000. Code in .text are mapped into MPC55xx's internal
FLASH, starting at 0x00000000.
When I attempt to link the code together, I get the error
U:\src\applications\comms/fatdog.c(35,1): relocation truncated to fit:
R_PPC_REL24 against symbol `ram1' defined in .ram_code section in
I googled the error and I think it means that the ram1() is too far away and
the branch address has been truncated to fit into the binary.
Other than assembler bel instruction, I have also tried bl, b and bea and
all of them gave the same link error.
I was wondering if anyone can give some insight on how I can get the MPC55xx
to branch between FLASH and SRAM?
Tehn Yit Chin
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