linux-kernel - Re: [PATCH v3 3/3] kselftest: Add new test for detecting unprobed Devicetree devices

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Date:   Mon, 6 Nov 2023 11:09:44 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Mark Brown <broonie@...nel.org>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
Cc:     Naresh Kamboju <naresh.kamboju@...aro.org>,
        Aishwarya TCV <aishwarya.tcv@....com>,
        kernelci@...ts.linux.dev, kernel@...labora.com,
        Guenter Roeck <groeck@...omium.org>,
        Bjorn Andersson <andersson@...nel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Frank Rowand <frowand.list@...il.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH v3 3/3] kselftest: Add new test for detecting unprobed
 Devicetree devices

On Thu, Nov 2, 2023 at 12:36 PM Mark Brown <broonie@...nel.org> wrote:
>
> On Thu, Nov 02, 2023 at 07:15:58PM +0530, Naresh Kamboju wrote:
> > On Thu, 2 Nov 2023 at 17:41, Aishwarya TCV <aishwarya.tcv@....com> wrote:
>
> > > https://storage.kernelci.org/mainline/master/v6.6-9152-gdeefd5024f07/arm64/defconfig%2Bkselftest/gcc-10/logs/kselftest.log
>
> ...
>
> > May be due to, A loop of symlinks that are pointing to self / same files ?
>
> Right, it does look like something bad is going on with symlinks:
>
> > > '/tmp/kci/linux/tools/testing/selftests/../../../build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/build/source/tools/testing/selftests/powerpc/vphn/vphn.c'
>
> > Please build by using tuxmake and validate builds are working.
>
> Note that tuxmake does an in tree build of kselftest:
>
>   make --silent --keep-going --jobs=8 O=/home/tuxbuild/.cache/tuxmake/builds/1/build INSTALL_PATH=/home/tuxbuild/.cache/tuxmake/builds/1/build/kselftest_install ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- 'CC=sccache aarch64-linux-gnu-gcc' 'HOSTCC=sccache gcc' kselftest-install
>
> and does it's own tarball build too, whereas kernelci does an out of
> tree build and uses kselftest-gen_tar:
>
>   make KBUILD_BUILD_USER=KernelCI FORMAT=.xz ARCH=arm64 HOSTCC=gcc CROSS_COMPILE=aarch64-linux-gnu- CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- CC="ccache aarch64-linux-gnu-gcc" O=/tmp/kci/linux/build -C/tmp/kci/linux -j10 kselftest-gen_tar
>
> and that the error is in the dt-extract-compatibles program which is
> part of the kernel (well, imported into the kernel from dtc upstream):
>
>   File "/tmp/kci/linux/tools/testing/selftests/../../../scripts/dtc/dt-extract-compatibles", line 107, in <module>
>     compat_ignore_list.extend(parse_compatibles_to_ignore(f))
>
> This all suggests that something to do with how the build is set up is
> resulting in the source symlink that gets created for out of tree builds
> blowing up, I guess it's not specifically the DT stuff that's blowing it
> up but rather that it's tripping over an existing bug.  Really does look
> like a legitimate bug though, the source link is set up by the in tree
> kernel build infrastructure.
>
> I did poke a bit at reproducing outside of the KernelCI scripts but
> didn't manage to yet.

I can repro with "make dt_compatible_check". The problem is with an
'out of tree' build within the tree. That's my normal setup, but the
difference is I have ".build" directories. If I use "build" instead,
then I can repro. The issue is the iglob will recurse into "build" but
not hidden directories (by default). There's no option to not follow
symlinks which would solve this (there is an open python issue since
2017 to add it). I don't see a simple solution in python other than
getting a full list with glob(), convert to absolute paths, and remove
duplicates. I imagine that will be somewhat slow.

A simple solution would be instead of passing the source tree root to
dt-extract-compatibles, pass 'arch', 'drivers', and 'sound' instead.
There shouldn't be compatibles anywhere else.

Rob