Hi,
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 ram1(void)
{
ram(123);
}
void flash1(unsigned int y)
{
unsigned int x;
x = x + y;
}
void flash(void)
{
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
U:\src\applications\comms\fatdog.o
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?
Many thanks,
Tehn Yit Chin
I am just going to answer my own questions for future reference.
I did some searching on the internet and came across this note on the
the usenet comp.sys.powerpc.tech
http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.powerpc.tech/2005-11/msg00015.html
In summary, it performs a indirect jump to code via the CTR register.
The following code snippet show how it is done.
lis 9,0xFC00 /* Function is at 0xFC000000 */
mtctr 9
bctrl
On Fri, Jul 18, 2008 at 4:29 PM, Tehn Yit Chin [off-list ref] wrote:
Hi,
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 ram1(void)
{
ram(123);
}
void flash1(unsigned int y)
{
unsigned int x;
x = x + y;
}
void flash(void)
{
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 U:\src\applications\comms\fatdog.o
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?
Many thanks,
Tehn Yit Chin