[U-Boot] [PATCH] ARMv7: Fix linker errors across toolchain versions

[Albert ARIBAUD <albert.aribaud@free.fr>]

Le 01/12/2010 22:39, Albert ARIBAUD a ?crit :
> This one is a conundrum.
>
> Using 2010q1, building omap3_evm causes a linker warning
> "arm-none-linux-gnueabi-ld: u-boot: section .bss vma 0x8003e8f0 overlaps
> previous sections" while building omap3_beagle does not cause any linker
> warning.
>
> Both boards use the same armv7 u-boot.lds and have a .bss which is way
> bigger than the .rel.dyn plus .dynsym sections that it does overlay.
> IOW, they have a similar layout for .rel.dyn, .dynsym and .bss, but one
> gets the warning and one does not.
>
> The one difference a readelf shows is that for beagle, there is only one
> segment:
>
> 00  .text .rodata .hash .data .got.plt .u_boot_cmd .rel.dyn .dynsym
>
> While for evm there is
>
> 00  .text .rodata .hash .data .got.plt .u_boot_cmd .rel.dyn .bss
> 01  .dynsym
>
> Note that .bss has appeared in segment 00 for evm, whereas it was absent
> for beagle, and that .dynsym was rejected to a second segment -- why? I
> don't know.
>
> Note: I've tried with putting input sections .rel.dyn and .dynsym into a
> single output section .rel.dyn: this makes the second segment disappear,
> but for evm the warning remains and .bss remains in the segment.

I have a tiny clue.

Starting with the fact that the linker issue is only for one board, 
omap3_evm, I looked up the board-specific code. First thing that I 
noticed was

	static u8 omap3_evm_version;

I changed this to

	static u8 omap3_evm_version = 1;

so that the static was moved out of BSS and the linker warning 
disappeared (reminder: v2010.12-rc2, omap3_evm, arm-2010q1).

Now this is not the first static BSS variable we use in U-Boot, and the 
others did not cause linker warnings (not *all* the others, at least), 
so the real cause is yet unknown to me. But that's at least a lead we 
can follow.

If this BSS variable is used before relocation (I haven't checked this), 
then anyway it'll have to move; in that case I'll keep an eye on this 
linker warning and try to sort it out if I get time.

Amicalement,
-- 
Albert.