[yocto] binutils 2.29.1 ARM Thumb kernel problem

[Chris Elledge]

Unfortunately, removing the "+1" doesn't work. That results in a kernel
which claims to start, but doesn't progress.

Changing it to an "|1" also doesn't work due to this error:
arch/arm/kernel/entry-common.S:117: Error: invalid operands (.text and
*ABS* sections) for `|'

Doing this to the badr macro:
 #ifdef CONFIG_THUMB2_KERNEL
  adr\c \rd, \sym
  orr\c \rd, \rd, #1
 #else

Is giving me a "Bad Linux ARM zImage magic!" error on boot

So, I don't think it's an easy change to the kernel.

-Chris

On Wed, Apr 4, 2018 at 4:04 PM, Andre McCurdy <armccurdy at gmail.com> wrote:

> 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
>
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