Hello Albert,
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 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.
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 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.
The good news is, I can spare a couple more hours today on this. I'll let you all know how this fares!
Thats good news! How much did the image size increase with this table?
./MAKEALL edminiv2 results:
text data bss dec hex filename 141376 4388 16640 162404 27a64 ./u-boot (for GOT reloc) 150160 3819 16640 170619 29a7b ./u-boot (for ELF reloc)
u-boot.bin size in bytes:
145764 (for GOT reloc) 153976 (for ELF reloc)
Huh...
The .rel.dyn table is 18472 bytes, and should eventually shrink by half, losing about 9 KB. That would bring the u-boot.bin size down to 145 KB, roughly the same size as GOT reloc -- plus we'd save a few code
... puuh ;-)
bytes since reloc fixup functions in board_init_r would not be needed any more.
Sounds good. And we can easy test this, by defining CONFIG_RELOC_FIXUP_WORKS for all arm boards ...
And I am willing to test your efforts on AT91 here, maybe you can send me the changes to .lds and start.S beforehand so I can see what type of relocation info gets produced here.
I'll post an RFC patch within one or two hours.
Thanks! I am wating for it, and try your patches too.
bye, Heiko