[Buildroot] Help to fix Microblaze issues in Buildroot

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Wed Nov 20 10:10:27 UTC 2013

Dear Alvaro Gamez,

On Wed, 20 Nov 2013 11:03:59 +0100, Alvaro Gamez wrote:

> Sorry for the big delay on this issue.
> Now that I've spent a few hours looking at the code, I can firmly say this
> is a compiler bug.
> I've studied beecrypt's sha384.c code (openssl and others implement exactly
> the same code from a common source) and I've managed to reduce the code to
> what I think is a minimal example of bug triggering code.
> After requesting gcc to preprocess the source, the same error still
> happens. Almost any minimal change I've tried to the preprocessed source
> makes the error go away (indexes or values seem to be irrelevant, I've just
> mantained the numbers the code came from). An optimization flag is required
> to trigger the bug (-Os, -O1,2,3). I haven't been successful trying to find
> which specific optimization flag is the one that causes the error.
> I've manually merged both (original and preprocessed files) to ease the
> analysis of the original source code and the resulting code. I'm sorry I
> can't provide any more information, I really don't have any grasp of gcc's
> internals.

Thanks! In fact, Spenser submitted patches to add support for
Microblaze in the internal toolchain backend. This is useful because
the pre-built external toolchains that we have been using until now are
quite old, and not maintained by Xilinx.

Therefore, the plan is, I believe:

 (1) Merge Spenser's patches to add Microblaze internal toolchain

 (2) Remove the broken Microblaze external toolchains

 (3) Hopefully, convince Xilinx to also provide pre-built external
 toolchains that are up-to-date. This will have to be done by people
 having contacts within Xilinx.

Best regards,

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering

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