On 04/10/10 19:28, Albert ARIBAUD wrote:
Le 04/10/2010 09:27, Reinhard Meyer a écrit :
Dear Albert ARIBAUD,
Right now I can build (not run, mind you) u-boot for edminiv2 without -fPIC/-fPIE, with -pie and a modified u-boot.lds and start.S. Almost all
Any reason to do it in assembler? Have a look at arch/i386/lib/board.c board_init_f() (especially if you apply my latest patch series)
of the .rel.dyn fixup entries are type 23, that is, relative to the base address, which is good. However, here are about ten at the end which are type 2 -- symbol-relative -- and I am studying them in order to see if they are needed.
Hmm, for x86 they are all type 8 (R_386_RELATIVE) which are a simple Base + Addend (B + A) entries
Type 23 is R_ARM_RELATIVE which are also B + A (although they can also by S + A whatever that means)
If type 23 relocations are all that is needed, then a first ARM ELF relocation implementation should 'simply' trade GOT vs .rel.dyn relocation in start.S (I am almost there) and remove fixups in
Removing fixups - sweet, oh so sweet ;)
board_init_r. Start.S would apply type 23 fixups only and ignore the rest. Later on we could add a build stage to rewrite the .rel.dyn section as suggested, by filtering out non-type-23 relocs and keeping only the address part of type-23 ones, reducing the .rel.dyn table roughly by half.
Also non type-8 for x86 - If all arches reduce down to a single relocation type in .rel.dyn then we can ignore the type and simply strip all the 'type' fields.
[snip]
A rather wild, but quite arch independant additional "build stage" for relocation would be to link u-boot for two different TEXT_BASE values e.g. TEXT_BASE (as desired) and TEXT_BASE+0x00010010. A special "diff" tool should find the 32 bit places where relocation is required and add a table to the end of u-boot.bin... (Just a rough idea)
I don't think we need to - everything should be handled by .rel.dyn. I wrote a diff tool to do as you suggest, but I have no need for it now
Looks like we could be onto a winner :)
Regards,
Graeme