Thanks for your tip and sorry for my ambiguit question.

When I read the relocate_code function in cpu/mpc8xx/start.S, I found the code below:

============================================================================= 512 sub r15, r10, r4 513 514 /* First our own GOT */ 515 add r14, r14, r15 516 /* then the one used by the C code */ 517 add r30, r30, r15 =============================================================================

And I checked the dis-assemble code, and R30 was used as a pointer, but which specification documentes this usage or it is just GCC's flavor?

2009/8/12 Kumar Gala galak@kernel.crashing.org:

On Aug 12, 2009, at 8:46 AM, Gao Ya'nan wrote:

...

I find nothing about this in (E)ABI specification(perhaps some old), so, where is it?

You want the ABI that is available here:

http://refspecs.freestandards.org/elf/elfspec_ppc.pdf

The EABI is just extensions on top of it.

• k