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

Arnaldo Carvalho de Melo
2025-10-01T18:25:59Z

On Wed, Oct 01, 2025 at 04:22:17PM +0100, Leo Yan wrote:
> 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?

It was in all alpine versions I have containers to test on:

toolsbuilder@five:~$ grep FAIL dm.log.old/summary
3 71.85 almalinux:9-i386 : FAIL clang version 17.0.6 (AlmaLinux OS Foundation 17.0.6-5.el9)
5 78.60 alpine:3.16 : FAIL gcc version 11.2.1 20220219 (Alpine 11.2.1_git20220219)
6 59.77 alpine:3.17 : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r4)
7 56.89 alpine:3.18 : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r10)
8 60.86 alpine:3.19 : FAIL gcc version 13.2.1 20231014 (Alpine 13.2.1_git20231014)
9 60.18 alpine:3.20 : FAIL gcc version 13.2.1 20240309 (Alpine 13.2.1_git20240309)
10 64.58 alpine:3.22 : FAIL gcc version 14.2.0 (Alpine 14.2.0)
11 63.36 alpine:edge : FAIL gcc version 14.2.0 (Alpine 14.2.0)
toolsbuilder@five:~$

GEN /tmp/build/perf/python/perf.cpython-312-x86_64-linux-musl.so
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:~
$

lemme try to reapply those patches and get the
tools/perf/feature/test-libelf.make.output and
tools/perf/feature/test-glibc.make.output files.

- Arnaldo