[ELDK] eldk-5.5.2 issues

[Wolfgang Denk]

Dear Albrecht,

In message <1414433699.5968.2 at deneb.(none)> you wrote:
>
> Just to understand your statement correctly: do you recommend to use
> ELDK 5.4 for the PowerPC instead of ELDK 5.5.x (I'm working with the
> Freescale MPC5200 and the QorIQ P2020 processors)?

I have to admit that I am not in a position yet to give any
recommendations based on deeper knowledge or understanding;
I cannot even tell if the observed effects are known GCC bugs, or if
the fact that the same effects are no longer present in 4.9.1 is
because a bug was detected and fixed, or just by pure chance.

> Does this apply to the kernel only, or also to user-space software,
> or to u-boot?

THis applies at least to U-Boot and Kernel, or more generaly to all
kinds of code where you take special efforts when arranging things
like the stack layout and/or the image linking.

I got bitten (on a MPC5200 by the way) by the fact that GCC 4.8.x
fails to provide relocation information for symbols in the (new)
.data.rel.ro and .data.rel.ro.local segments.  You could call this a
deciciency in the U-Boot linker scripts, but then, it got "fixed" (or
changed again) in gcc 4.9.1.  For details, see [1] and [2].

The ARM Linux kernel folks even discuss blacklisting GCC 4.8.x for
other reasons, see [3]

So it's only observations of such ill effects, not real understanding
of which GCC bugs are causing these, or if fixes are available, and
when these were (or get) merged.

I can only say that I currently use gcc 4.7.x (from ELDK 5.4) for all
production builds where I need working code, resp. gcc 4.9.1 (what
will become ELDK v5.7) for testing.

This is just my $ 0.02.  Your mileage may vary.

[1] http://article.gmane.org/gmane.comp.boot-loaders.u-boot/199062
[2] http://article.gmane.org/gmane.comp.boot-loaders.u-boot/199076
[3] https://lkml.org/lkml/2014/10/10/272

Best regards,

Wolfgang Denk

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