Re: [PATCH] perf build: Improve fix for "argument list too long" error

[Ian Rogers]

On Mon, Sep 28, 2026 at 2:15 AM James Clark <james.clark@xxxxxxxxxx> wrote:
>
>
>
> On 28/09/2026 09:55, Benoît Monin wrote:
> > The orphaned pmu-events JSON files are passed to the shell via
> > `echo "$^"`, which puts the whole list into a single argument. With
> > a long enough output directory path and enough files, exec'ing
> > /bin/sh fails with:
> >
> >    make[5]: /bin/sh: Argument list too long
> >    make[5]: *** [pmu-events/Build:228: prune_orphans] Error 127
> >
> > This only happens with out-of-tree builds, when setting O= to a
> > relatively long path.
> >
> > To reproduce, build once with JEVENTS_ARCH=all, then rebuild with
> > a smaller JEVENTS_ARCH without cleaning first, so the leftover files
> > become orphans. Using nds32 (which leaves ~1100 orphans), an output
> > path of only ~70 characters is already enough to trigger it:
> >
> >    OUT=/any/long/path (at least 70 characters)
> >    make -C tools/perf JEVENTS_ARCH=all   O=$OUT -j$(nproc)
> >    make -C tools/perf JEVENTS_ARCH=nds32 O=$OUT -j$(nproc)
> >
> > Express the orphan file list as paths relative to $(OUT_DIR) by
> > stripping the common prefix and restoring it with printf, the same
> > approach used in scripts/Makefile.clean, so the shell arguments stay
> > short.
> >
> > Fixes: b6712d91f8f5 ("perf build: Prevent "argument list too long" error")
> > Suggested-by: Vladimir Kondratiev <vladimir.kondratiev@xxxxxxxxxxxx>
> > Signed-off-by: Benoît Monin <benoit.monin@xxxxxxxxxxx>
> > Tested-by: Vladimir Kondratiev <vladimir.kondratiev@xxxxxxxxxxxx>
>
> Reviewed-by: James Clark <james.clark@xxxxxxxxxx>

Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian