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[209.85.218.50]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ba455044410sm516601566b.47.2026.04.22.01.07.00 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Apr 2026 01:07:00 -0700 (PDT) Received: by mail-ej1-f50.google.com with SMTP id a640c23a62f3a-b9e00649769so723595866b.3 for ; Wed, 22 Apr 2026 01:07:00 -0700 (PDT) X-Forwarded-Encrypted: i=1; AFNElJ/zGdvwM91c4c9h5HIY0Vd8hWVCsMNs49ed7qlnxuQdzldj5kgvE5wgooi//Xgdsl5t3DKJltfM4BY9elU=@vger.kernel.org X-Received: by 2002:a17:906:4fc5:b0:b9b:ddb2:b1c1 with SMTP id a640c23a62f3a-ba418f7f625mr936456766b.21.1776845219289; Wed, 22 Apr 2026 01:06:59 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20260422071541-9a295128-d913-418f-a21c-1386fca30290@linutronix.de> <20260422092713-4021a1a5-3a54-4260-878a-aec1bef3f8c7@linutronix.de> In-Reply-To: <20260422092713-4021a1a5-3a54-4260-878a-aec1bef3f8c7@linutronix.de> From: Ricardo Ribalda Date: Wed, 22 Apr 2026 16:06:45 +0800 X-Gmail-Original-Message-ID: X-Gm-Features: AQROBzA7vfrwO2plpLpwVGaJQHR2MKiQUcm7cyVmWYAcKsQQIyoUjhDJYfCBMLg Message-ID: Subject: Re: New warning in linus/master To: =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= Cc: linux-arm-kernel@lists.infradead.org, Linux Kernel Mailing List , linuxppc-dev@lists.ozlabs.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Thomas On Wed, 22 Apr 2026 at 15:32, Thomas Wei=C3=9Fschuh wrote: > > On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote: > > On Wed, 22 Apr 2026 at 13:57, Thomas Wei=C3=9Fschuh > > wrote: > > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: > > > > Media-CI has found a couple of new warnings in the latest kernel > > > > version for aarch64 and powerpc. They get fixed with this patch and > > > > before moving I wanted to know if this was under your radar. > > > > > > Thanks for the report. I was not aware of these so far. > > > > > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vd= so/Makefile > > > > index 7dec05dd33b7..65914842fae0 100644 > > > > --- a/arch/arm64/kernel/vdso/Makefile > > > > +++ b/arch/arm64/kernel/vdso/Makefile > > > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o =3D $(CC_FLAGS_ADD_VDSO) > > > > CFLAGS_vgetrandom.o =3D $(CC_FLAGS_ADD_VDSO) > > > > > > > > ifneq ($(c-gettimeofday-y),) > > > > - CFLAGS_vgettimeofday.o +=3D -include $(c-gettimeofday-y) > > > > + CFLAGS_vgettimeofday.o +=3D -include $(c-gettimeofday-y) > > > > -Wno-maybe-uninitialized > > > > endif > > > > > > (...) > > > > > > I'd like to know exactly what is going on before suppressing the warn= ing. > > > It is a non-standard warning, only enabled by *some* of the vDSO buil= ds > > > for some reason. > > > > > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipeline= s/1649144/test_report?job_name=3Dcross-gcc > > > > > > While I was able to download a configuration from this job and also u= se the > > > same container image, I can not reproduce the issue. Is the configura= tion the > > > full one or only the template? > > > > > > Could you provide full reproduction steps? > > > > You can try repro with: > > > > work/linux $ podman run -v .:/workdir/ --rm -it > > registry.freedesktop.org/linux-media/media-ci/build:latest > > $ cd /workdir > > $ CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make allyesconfig > > $ CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make > > arch/arm64/kernel/vdso/vgettimeofday.o > > > > The gcc version discrepancy is because I the error was due to old gcc > > version and I was playing around with that... but it fails in both > > gcc14 and gcc15 > > Ack. > > > You can try with debian testing with > > work/linux$ podman run -v .:/workdir/ --rm -it debian:testing > > $ apt-get update > > $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libs= sl-dev bc > > $ cd /workdir > > $ CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make allyesconfig > > $ CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make > > arch/arm64/kernel/vdso/vgettimeofday.o > > Both reproducers do *not* reproduce the issue for me. > (It is more or less exactly what I tried before) Ok, I think I found what is going on. media-ci was forcing KCFLAGS=3D-Wmaybe-uninitialized https://gitlab.freedesktop.org/linux-media/media-ci/-/blob/main/test-build.= sh?ref_type=3Dheads#L29 And something has changed in the kernel in the last version that triggers a (hopefully) false positive. can you try with: CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make KCFLAGS=3D-Wmaybe-uninitialized allyesconfig CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make KCFLAGS=3D-Wmaybe-uninitialized prepare ? > > Please note that this line does not work in general: > $ CROSS_COMPILE=3Daarch64-linux-gnu- ARCH=3Darm64 make arch/arm64/kernel/= vdso/vgettimeofday.o > > The vDSO object files can not be built in this way like regular kernel ob= ject > files and will produce a compiler error, but not the one under discussion= . > Instead the vDSO on arm64 is built during the 'make prepare' phase. > (Other architectures work differently, of course...) > > (...) > > > Thomas --=20 Ricardo Ribalda