Re: [RFC PATCH 3/6] tools: build perf in tools_build

[Sasha Levin <sashal@kernel.org>]

On Mon, Oct 12, 2026 at 03:07:10PM -0700, Ian Rogers wrote:
> On Sun, Oct 11, 2026 at 4:36 PM Sasha Levin <sashal@kernel.org> wrote:
> > +# Every optional feature off, so the result does not depend on which
> > +# libraries are installed
> > +perf-flags-$(CONFIG_TOOLS_BUILD_PERF_MINIMAL) += \
> > +       NO_LIBELF=1 NO_LIBTRACEEVENT=1 NO_JEVENTS=1 NO_LIBPYTHON=1 NO_LIBDW=1 \
> > +       NO_LIBBPF=1 BUILD_BPF_SKEL=0 NO_SLANG=1 NO_GTK2=1 NO_AIO=1 \
> > +       NO_BACKTRACE=1 NO_DEMANGLE=1 NO_LZMA=1 NO_LIBZSTD=1 NO_ZLIB=1 \
> > +       NO_LIBNUMA=1 NO_LIBUNWIND=1 NO_LIBLLVM=1 NO_CAPSTONE=1 NO_LIBPFM4=1 \
> > +       NO_SDT=1 NO_JVMTI=1 NO_LIBDEBUGINFOD=1 NO_BABELTRACE2=1 NO_RUST=1 \
> > +       NO_SHELLCHECK=1 NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX32=1
>
> It seems unfortunate to maintain this list here, we also have a
> minimal target as a build test here:
> https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/tests/make?h=perf-tools-next#n123
> I wonder we should just add support for a MINIMAL=1 variable in
> tools/perf/Makefile.config and have that set these other variables.

Yup :(

What allmodconfig really wants from perf is what allmodconfig already does for
the kernel: build everything the environment supports and skip the rest. A
kernel option that needs something the toolchain lacks just ends up off rather
than breaking the build.

perf has no mode like that I think? A default build fails when libelf,
libtraceevent or python is missing, so an arm64 cross build, or a native build
without libtraceevent-dev, breaks. Turning everything off was the only way I
found around that.

Would it make sense to add such a mode to perf instead of MINIMAL=1?  A missing
library would disable its feature with a warning rather than fail the build,
and the mode could skip shellcheck, mypy and pylint too. allmodconfig would
then build as much of perf as the host allows.

-- 
Thanks,
Sasha