Le 03/10/2010 10:44, Graeme Russ a écrit :
Bill just said that -pic (or, for ARM, -fPIC or -fPIE) was unnecessary for relocation. You seem to imply it actually is... In my experience, -fPIC and-fPIE do increase code by adding GOT relocation to symbols that need fixing, so they would indeed be redundant to any other relocation mechanism -- I just did some test with basic code and this seems to confirm, no -fPIx is needed to get relocation the way you do on ARM.
Just to clarify -fpic is a compiler option, -pic is a linker option. x86 has no compile time relocation options (therefore no referencing .got etc). Using the link time pic option produces the relocation data table (.rel.dyn) which must be pre-processed before execution can begin at the relocated address
Thanks for clarifying, Graeme.
This is consistent with the ARM compile-time options -fPIC/-fPIE vs link-time option -pie. So there may be at least an interest in investigating ELF-style relocation on ARM and comparing it to GOT-based relocation in terms of FLASH and RAM sizes and code speed.
Cheers,
Graeme
Amicalement,