[yocto] binutils 2.29.1 ARM Thumb kernel problem

[Chris Elledge]

I recently upgraded my Yocto based project to Yocto 2.4.2, and I
encountered a problem when building my custom kernel for an AT91 SAMA5D3X
platform. I've been using an ARM Thumb2 kernel for a while successfully
until this release. It appears that the issue stems from the change to
binutils version 2.29.1.

Here's a good description of the problem:
https://patchwork.kernel.org/patch/10072695/

I tried out their test script, and it flagged the arm-poky-linux-gnueabi-
toolchain built by Yocto 2.4.2 as being buggy. Has anyone else encountered
this problem and figured out a way around it without disabling Thumb
compilation of the kernel?

Thanks,
Chris

The bug showed up in my kernel with the following oops at kernel boot:
Internal error: Oops - undefined instruction: 0 [#1] PREEMPT THUMB2
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 4.9.91-custom #53
Hardware name: Atmel SAMA5
task: df448000 task.stack: df44a000
PC is at ret_fast_syscall+0x2/0x54
LR is at SyS_brk+0xe9/0x104
pc : [<c0105e62>]    lr : [<c016bca1>]    psr: 60000013
sp : df44bfa8  ip : 50c5387d  fp : 00001000
r10: 00000000  r9 : df44a000  r8 : c0106044
r7 : 0000002d  r6 : b6f3e050  r5 : 00010034  r4 : 00000008
r3 : df448000  r2 : ffff0001  r1 : 00000000  r0 : 00bda000
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 50c5387d  Table: 3ec84059  DAC: 00000051
Process init (pid: 1, stack limit = 0xdf44a210)
Stack: (0xdf44bfa8 to 0xdf44c000)
bfa0:                   00000008 00010034 00000000 00000001 beddcfb8
00000000
bfc0: 00000008 00010034 b6f3e050 0000002d 00000000 00000001 00000001
00001000
bfe0: 00000001 beddce3c b6f54cf4 b6f55b28 20000010 00000000 ec846eac
80cafe65
Code: 0000bd08 00000000 00000000 b6720000 (1000f8d9)
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