On Fri, 25 Jul 2008 19:28:48 +0200 kenneth johansson kenneth@southpole.se wrote:
I was afraid that what was needed was more or less a complete linker but it looks like if one generate the dynamic reloc table a much simpler linker(relocation function) is needed. Still probably a lot more complex than the GOT and fixup code that is just a loop over a table. We may need a case also ;-)
Hmm...looks like linking with -pie (or --pic-executable) does something vaguely resembling the trick. But I don't know what vintage of ld you need for this to be available and actually work...
hskinnemoen@siona:~/work/u-boot/master$ avr32-linux-readelf -d u-boot
Dynamic section at offset 0x1b8f0 contains 12 entries: Tag Type Name/Value 0x00000004 (HASH) 0x182ac 0x00000005 (STRTAB) 0x18260 0x00000006 (SYMTAB) 0x18150 0x0000000a (STRSZ) 74 (bytes) 0x0000000b (SYMENT) 16 (bytes) 0x00000003 (PLTGOT) 0x1ae70 0x70000001 (Processor Specific: 70000001) 0xe6c 0x00000015 (DEBUG) 0x0 0x00000007 (RELA) 0x1833c 0x00000008 (RELASZ) 6996 (bytes) 0x00000009 (RELAENT) 12 (bytes) 0x00000000 (NULL) 0x0
The dynamic relocation section became surprisingly large. I wonder if we actually manage to manually relocate all those buggers...I checked a couple of them and in both cases it looked like something that needed to be relocated, but I couldn't find any code that actually did it.
One example from common/cmd_itest.c:
op_tbl_t op_table [] = { { "-lt", LT }, { "<" , LT }, { "-gt", GT }, { ">" , GT }, { "-eq", EQ }, { "==" , EQ }, { "-ne", NE }, { "!=" , NE }, { "<>" , NE }, { "-ge", GE }, { ">=" , GE }, { "-le", LE }, { "<=" , LE }, };
Does this really work without any relocation? Or is it being relocated and I'm just too blind to see it?
The symbol tables can probably be made smaller with some careful ldscript tweaking.
Haavard