Is there any reason why when partial linking with ld -r that
local symbols cannot be completely resolved and therefore
removed from the symbol table?
It seems that a link with ld -r still requires the local
symbols to be kept; only on the final link to produce
a static executable are the local symbols finally
resolved. For example, following the symbol p1 through
the process below.
Thanks for any insight!
Ian
% cc -c -o a.o a.c
% nm a.o
00000044 T global
00000000 T main
0000002c T p1
U p2
U printf
% # p1 is global, but not really need beyond this [group of] file[s].
% # Make p1 local
% objcopy -L p1 a.o
% # Partial link
% ld -r -o a1.o a.o
% # Have a look at the symbol table; p1 is local.
% nm a1.o
00000044 T global
00000000 T main
0000002c t p1
U p2
U printf
% # But the code still requires the symbol, see address 0x20:
objdump -d a1.o
a1.o: file format elf32-i386
Disassembly of section .text:
00000000 <main>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 83 ec 08 sub $0x8,%esp
6: 83 e4 f0 and $0xfffffff0,%esp
9: b8 00 00 00 00 mov $0x0,%eax
e: 29 c4 sub %eax,%esp
10: 83 ec 0c sub $0xc,%esp
13: 68 00 00 00 00 push $0x0
18: e8 fc ff ff ff call 19 <main+0x19>
1d: 83 c4 10 add $0x10,%esp
20: e8 fc ff ff ff call 21 <main+0x21>
25: e8 fc ff ff ff call 26 <main+0x26>
2a: c9 leave
2b: c3 ret
0000002c <p1>:
2c: 55 push %ebp
2d: 89 e5 mov %esp,%ebp
2f: 83 ec 08 sub $0x8,%esp
32: 83 ec 0c sub $0xc,%esp
35: 68 06 00 00 00 push $0x6
3a: e8 fc ff ff ff call 3b <p1+0xf>
3f: 83 c4 10 add $0x10,%esp
42: c9 leave
43: c3 ret
00000044 <global>:
44: 55 push %ebp
45: 89 e5 mov %esp,%ebp
47: 83 ec 08 sub $0x8,%esp
4a: 83 ec 0c sub $0xc,%esp
4d: 68 0a 00 00 00 push $0xa
52: e8 fc ff ff ff call 53 <global+0xf>
57: 83 c4 10 add $0x10,%esp
5a: c9 leave
5b: c3 ret
% Indeed, we cannot remove it.
% objcopy -N p1 a1.o big.o
BFD: big.o: symbol `p1' required but not present
objcopy: big.o: No symbols
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