Hi,
I'm new to U-Boot. Here I got some questions when I read the following code in include/ppc_asm.tmpl:
#define START_GOT \ .section ".got2","aw"; \ .LCTOC1 = .+32768
#define END_GOT \ .text
#define GET_GOT \ bl 1f ; \ .text 2 ; \ 0: .long .LCTOC1-1f ; \ .text ; \ 1: mflr r14 ; \ lwz r0,0b-1b(r14) ; \ add r14,r0,r14 ;
#define GOT_ENTRY(NAME) .L_ ## NAME = . - .LCTOC1 ; .long NAME
#define GOT(NAME) .L_ ## NAME (r14)
1. As what I understand, after lwz r0,0b-1b(r14) , LOCTOC1-1f is stored in r0, but I totally lost with the following instruction:
add r14,r0,r14. What's in r14 now. Is the value of label "1f" the absolute address or relative address of the code it labels or whatever else?
2. What do the #define directives do here? I noticed there are spaces before and after "##"; what's the value of NAME in ".long NAME". In cup/mpc8xx/start.S, some code such as "lwz r7, GOT(_start)" invokes the macro.
Any idea will be truly appreciated.
David