11.1 EDK - "ERROR: relocation truncated to fit: R_PPC_REL24 myFunction"
Description
Keywords: R_PPC, link, powerpc-eabi-ld
When I attempt to link a PowerPC application that contains functions separated by more than 26 bits of address space, the following error message appears:
"Error: relocation truncated to fit: R_PPC_REL24 <myFunction>"
Solution
The default assembly command used by the GCC compiler to branch to a new function is "bl," which allows at most a 26-bit offset to the current address. If a function is separated from the function from which it is called by greater than 26 bits, the attribute "longcall" can be placed on the function in C to specify that the compiler must use a longer branch to reach the function. This can be specified, as follows, in the function declaration:void myFunction(void) __attribute__ ((longcall));
Solution 2
You can make all functions perform a long jump by adding the following option to the extra compiler switches:
-mlongcall
Solution 3
Alternatively, the function can be called as a function pointer, which is treated as being inherently FAR by the compiler.
Example:
void myFunction(void) {/*your code here*/};
int main()
{
void (*f2)(void);
f2 = myFunction;
f2();
}
Solution 4
Finally, a function can also be called as a pointer with an absolute address; for example, a jump from a bootloader to the start address of code.
Example:
int main()
{
void (*f2)(void);
f2 = (void *) 0x00001000;
f2();
}