[U-Boot] Relocation issue - need help!

[Wolfgang Denk]

Dear Joakim, dear Dirk,

In message <OF14C3D470.864842B6-ONC1257D7A.002471AC-C1257D7A.0024DEC4 at transmode.se> you wrote:
>
> Ouch, that was a nasty surprise.

Indeed.

> > In my original mail I referenced this potential solution, at least it
> > worked for me:
> > https://gcc.gnu.org/ml/gcc-help/2014-02/msg00054.html
> 
> That looks like the correct fix but I presume both .data.rel.ro and
> data.rel.ro.local should be added?

I can confirm:

1) The problem was observed with gcc 4.8.1 [as in Yocto 1.5.x / ELDK
   5.5.x].

2) Switching back to gcc 4.7.2 [as in Yocto 1.4 / ELDK 5.4] makes the
   problem go away.

3) Switching forward to gcc 4.9.1 [as in Yocto 1.7 / ELDK 5.7] makes
   the problem go away.

4) For the problemativ 4.8.x versions of GCC, the following patch
   apparently solves the problem for my (MPC5200 based) board - guess
   this would have to be applied to all .lds files...

diff --git a/arch/powerpc/cpu/mpc5xxx/u-boot.lds b/arch/powerpc/cpu/mpc5xxx/u-boot.lds
index cd9e23f..82c86d7 100644
--- a/arch/powerpc/cpu/mpc5xxx/u-boot.lds
+++ b/arch/powerpc/cpu/mpc5xxx/u-boot.lds
@@ -27,6 +27,8 @@ SECTIONS
   {
     _GOT2_TABLE_ = .;
     KEEP(*(.got2))
+    KEEP(*(.data.rel.ro))
+    KEEP(*(.data.rel.ro.local))
     KEEP(*(.got))
     PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
     _FIXUP_TABLE_ = .;

Given that GCC 4.9.1 apparently solves this issue I wonder which
approach we should take?

Should we blacklist GCC 4.8.x (and 4.9.0) like the kernel folks are
doing [1] ?

[1] https://lkml.org/lkml/2014/10/10/272

Best regards,

Wolfgang Denk

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