New warning in linus/master

[Thomas Weißschuh]

On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote:
> On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh
> <thomas.weissschuh at linutronix.de> 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/vdso/Makefile
> > > index 7dec05dd33b7..65914842fae0 100644
> > > --- a/arch/arm64/kernel/vdso/Makefile
> > > +++ b/arch/arm64/kernel/vdso/Makefile
> > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
> > >  CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
> > >
> > >  ifneq ($(c-gettimeofday-y),)
> > > -  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> > > +  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> > > -Wno-maybe-uninitialized
> > >  endif
> >
> > (...)
> >
> > I'd like to know exactly what is going on before suppressing the warning.
> > It is a non-standard warning, only enabled by *some* of the vDSO builds
> > for some reason.
> >
> > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc
> >
> > While I was able to download a configuration from this job and also use the
> > same container image, I can not reproduce the issue. Is the configuration 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=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 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 libssl-dev bc
> $ cd /workdir
> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 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)

Please note that this line does not work in general:
$ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make arch/arm64/kernel/vdso/vgettimeofday.o

The vDSO object files can not be built in this way like regular kernel object
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