[yocto] [meta-raspberrypi] poky linux build fails if ARM erratum mfix linker switch is specified

[Steve Pavao]

> On Nov 3, 2019, at 1:25 PM, Adrian Bunk <bunk at stusta.de> wrote:
> 
> On Sun, Nov 03, 2019 at 05:56:45PM +0000, Andrei Gherzan wrote:
>> On 3 November 2019 13:18:53 GMT, Khem Raj <raj.khem at gmail.com> wrote:
>>> On Sun, Nov 3, 2019 at 2:46 AM Andrei Gherzan <andrei at gherzan.ro>
>>> wrote:
>>>> I was thinking about this. The erratum seems to show that this
>>> applies
>>>> to all revisions of a53. So it sounds like we should add it in
>>>> `tune-cortexa53.inc`.
>>>> 
>>> 
>>> Up to r0b4 only so maybe not all a53 implementations are impacted
>>> 
>> 
>> As far as I know that is the latest revision. Do you mean that newer revision might come up with this fixed? 
> 
> It is fixed in some r0p4 implementations, indicated in REVIDR[8].
> 

I am closer to understanding why I experience an error when building with the ARM errata switches.

I believe it is related to 32-bit app support in my poky Linux 64-bit build (I add this to support vcgencmd and vcdbg 32-bit apps.)

When I remove the 32-bit support, the build completes OK.  As of now, adding the following seems to work fine to acheive this:

TARGET_CC_ARCH_append += " -mfix-cortex-a53-843419 -mfix-cortex-a53-835769”

Something in the following block seems to be the culprit.:

# for vcgencmd and vcdbg 32-bit executable support in the OS image (comment out for -c populate_sdk)
require conf/multilib.conf
MULTILIBS = "multilib:lib32"
DEFAULTTUNE_virtclass-multilib-lib32 = "armv7a"
IMAGE_INSTALL_append += " vcgencmd lib32-glibc lib32-libgcc lib32-libstdc++ vcdbg rpi-setup \
“

I will post again when I have localized the build problem further.  Maybe there’s some 64-bit vs. 32-bit build confusion going on, and the armv7a default tune switch for 32-bits is colliding with the errata switches.

- Steve Pavao
Korg R&D