[yocto] binutils 2.29.1 ARM Thumb kernel problem

[Andre McCurdy]

On Wed, Apr 4, 2018 at 9:14 AM, Andre McCurdy <armccurdy at gmail.com> wrote:
> On Wed, Apr 4, 2018 at 8:06 AM, Chris Elledge
> <celledge at digitallumens.com> wrote:
>> Thanks for the feedback. I rolled back binutils to 2.28.0 by copying the
>> yocto-2.3.3 binutils recipe directory into my custom layer. That has
>> resolved the issue.
>>
>> I can confirm that binutils 2.29.0 also has the problem. I went from
>> yocto-2.3 to 2.4.2 so I hadn't tried binutils 2.29.0 previously. There are
>> also reports that openssl and libavcodec are broken when targeting an ARM
>> Thumb2 platform with binutils 2.29.*
>
> Yes, that makes sense. The binutils change is in both 2.29.0 and
> 2.29.1 (and also in 2.30.0).
>
> The next useful experiment would be to stay with binutils 2.29.1 and
> apply a patch to revert the one particular commit which caused the
> change in behaviour:
>
>   https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=e645cf40b111daef4518a58547de577eb9379ccb

The experiment of patching the kernel would also be useful, since I
would guess that the final solution from upstream will involve a
change to the kernel rather than reverting the change to binutils.

Changing "+ 1" to "| 1" in the badr macro would be a universal
solution for all versions of binutils, but for a quick test with
binutils 2.29.1 you could simply remove the "+ 1" from the
CONFIG_THUMB2_KERNEL case (ie make the ARM and Thumb2 versions of the
macro identical).

  https://github.com/torvalds/linux/blob/master/arch/arm/include/asm/assembler.h#L197