Le 12/10/2010 19:11, Joakim Tjernlund a écrit :
Figured I should mention that I have added -msingle-pic-base(from ARM) which works nicely with -fpic(not sure if -fPIC is possible) and reduces
size
even more:
Since you seem to be following the same path as I did on ARM, I may as well ask: did you try removing -fPIC and -msingle-pic-base from compile options and adding -pie to the link options instead?
looked at it briefly but -pie is really massive. Each access needs a reloc entry, even if they access the same data.
Link option -pie generates ELF relocation and, on ARM at least, does a better job than GOT reloc, which does not fix handle pointers in initialized data while ELF reloc fixes them.
on ppc -mrelocatable does the job for you and adds fixup relocs. It a simple addon that should be fairly easy to add to other archs too.
And since ELF reloc does not modify code (it is a linker option), you
ehh, I think you need to reloc directly in the text segment.
end up with the same size for text+data+rodata. You do have a bigger FLASH image though, because the ELF reloc tables are bigger than the GOT
table; but you can git rid of them / not copy them to RAM once
relocated.
I don't think RAM is as much as a problem as flash is.
The move from -fPIC to ELF on ARM can be looked for in the elf_reloc branch of the u-boot-arm repo.
Yes, but I believe the ppc way is smaller once -fpic and -msingle-pic-base are used(In flash anyway). Also, I don't think you will be able to do true PIC in the future without PIC code.
Jocke