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SubjectRe: next/master bisection: baseline.login on rk3288-rock2-square
On 04/02/2021 16:01, Ard Biesheuvel wrote:
> On Thu, 4 Feb 2021 at 16:53, Guillaume Tucker
> <> wrote:
>> On 04/02/2021 15:42, Ard Biesheuvel wrote:
>>> On Thu, 4 Feb 2021 at 12:32, Guillaume Tucker
>>> <> wrote:
>>>> On 04/02/2021 10:33, Guillaume Tucker wrote:
>>>>> On 04/02/2021 10:27, Ard Biesheuvel wrote:
>>>>>> On Thu, 4 Feb 2021 at 11:06, Russell King - ARM Linux admin
>>>>>> <> wrote:
>>>>>>> On Thu, Feb 04, 2021 at 10:07:58AM +0100, Ard Biesheuvel wrote:
>>>>>>>> On Thu, 4 Feb 2021 at 09:43, Guillaume Tucker
>>>>>>>> <> wrote:
>>>>>>>>> Hi Ard,
>>>>>>>>> Please see the bisection report below about a boot failure on
>>>>>>>>> rk3288 with next-20210203. It was also bisected on
>>>>>>>>> imx6q-var-dt6customboard with next-20210202.
>>>>>>>>> Reports aren't automatically sent to the public while we're
>>>>>>>>> trialing new bisection features on but this one
>>>>>>>>> looks valid.
>>>>>>>>> The kernel is most likely crashing very early on, so there's
>>>>>>>>> nothing in the logs. Please let us know if you need some help
>>>>>>>>> with debugging or trying a fix on these platforms.
>>>>>>>> Thanks for the report.
>>>>>>> Ard,
>>>>>>> I want to send my fixes branch today which includes your regression
>>>>>>> fix that caused this regression.
>>>>>>> As this is proving difficult to fix, I can only drop your fix from
>>>>>>> my fixes branch - and given that this seems to be problematical, I'm
>>>>>>> tempted to revert the original change at this point which should fix
>>>>>>> both of these regressions - and then we have another go at getting rid
>>>>>>> of the set/way instructions during the next cycle.
>>>>>>> Thoughts?
>>>>>> Hi Russell,
>>>>>> If Guillaume is willing to do the experiment, and it fixes the issue,
>>>>> Yes, I'm running some tests with that fix now and should have
>>>>> some results shortly.
>>>> Yes it does fix the issue:
>>>> with Ard's fix applied to this test branch:
>>>> +clang +Nick
>>>> It's worth mentioning that the issue only happens with kernels
>>>> built with Clang. As you can see there are several other arm
>>>> platforms failing with clang-11 builds but booting fine with
>>>> gcc-8:
>>>> Here's a sample build log:
>>>> Essentially:
>>>> make -j18 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LLVM=1 CC="ccache clang" zImage
>>>> I believe it should be using the GNU assembler as LLVM_IAS=1 is
>>>> not defined, but there may be something more subtle about it.
>>> Do you have a link for a failing zImage built from multi_v7_defconfig?
>> Sure, this one was built from a plain next-20210203:
>> You can also find the dtbs, modules and other things in that same
>> directory.
>> For the record, here's the test job that used it:
> Thanks.
> That zImage boots fine locally. Unfortunately, I don't have rk3288
> hardware to reproduce.
> Could you please point me to the list of all the other platforms that
> failed to boot this image?

This is the list of platforms from I've gathered
which appeared to be impacted:


They were all booting next-20210203 with gcc-8 but not with
clang-11. I've run checks on a good share of them with your
patch applied and they're now booting with clang-11, just like
the rk3288 and imx6q platforms that were used for the bisections.

> To be honest, I am slightly annoyed that a change that works fine with
> GCC but does not work with Clang version
> 11.1.0-++20210130110826+3a8282376b6c-1~exp1~20210130221445.158
> (where exp means experimental, I suppose) is the reason for this

Well it's the standard one from the LLVM Debian package repo:

deb llvm-toolchain-buster-11 main

There's a slightly newer version, I doubt it would make any
difference in this respect unless there's a particular fix in

# apt policy clang-11
Installed: 1:11.1.0~++20210130110826+3a8282376b6c-1~exp1~20210130221445.158
Candidate: 1:11.1.0~++20210204120158+1fdec59bffc1-1~exp1~20210203230823.159

> discussion, especially because the change is in asm code. Is it
> possible to build with Clang but use the GNU linker?

As mentioned by Nick, it is using everything from LLVM except the
assembler - so not the GNU linker. I've now built a new Docker
container with the latest LLVM package version (.159) as well as
gcc-8-arm-linux-gnueabihf to try with the GNU linker and see if
that makes any difference. More on that shortly...


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