Re: [PATCH v2 0/8] perf build: Support building with Clang

Leo Yan
2025-10-01T15:22:19Z

On Wed, Oct 01, 2025 at 11:21:20AM -0300, Arnaldo Carvalho de Melo wrote:
> On Tue, Sep 30, 2025 at 05:54:48PM +0100, Leo Yan wrote:
> > This series adds support for building perf with Clang, following the
> > discussion in [1]. Because the Android NDK uses Clang by default,
> > enabling Clang builds naturally covers Android as well.
> >
> > The series is organized as follows:
> >
> > - Patches 1–2: Fix two bugs found with Clang.
> > - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
> > - Patches 7–8: Enable Clang in the Makefile and update the
> > documentation.
> >
> > Testing:
> >
> > - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
> > - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
> > - Android NDK r27d (latest LTS): cross-compiling (aarch64)
>
> LD /tmp/build/perf/util/perf-util-in.o
> LD /tmp/build/perf/perf-util-in.o
> AR /tmp/build/perf/libperf-util.a
> CC /tmp/build/perf/pmu-events/pmu-events.o
> LD /tmp/build/perf/pmu-events/pmu-events-in.o
> AR /tmp/build/perf/libpmu-events.a
> LINK /tmp/build/perf/perf
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + rm -rf /tmp/build/perf
> + mkdir /tmp/build/perf
> + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
> BUILD: Doing 'make -j28' parallel build
> Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el]. Stop.
> make[1]: *** [Makefile.perf:289: sub-make] Error 2
> make: *** [Makefile:76: all] Error 2
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + exit 1
> toolsbuilder@five:~$ cat dm.log/alpine\:3.22

A quick look: the build cannot find both libelf (feature-libelf=0) and
glibc (feature-glibc=0), thus lead to build failure. It is good to
know what the reason for the feature building failures:

tools/perf/feature/test-libelf.make.output
tools/perf/feature/test-glibc.make.output

I am not surprised for the failure of libelf (this is common case
that the package is not installed by default in a distro), but it is a
bit confused for the glibc feature failure.

It seems the issue occurs on Alpine 3.22, but the highest version
supported in container-build is 3.21 [1]. Could you confirm whether
the issue reproduces on other distros or versions?

Thanks,
Leo

[1] https://github.com/acmel/linux-tools-container-builds/tree/main/alpine