Messages in this thread | | | Date | Thu, 01 Sep 2022 16:22:06 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf: Ignore format attribut es with an unknown perf event attr field |
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On September 1, 2022 3:47:10 PM GMT-03:00, Rob Herring <robh@kernel.org> wrote: >If the kernel exposes a new perf_event_attr field in a format attr, perf >will return an error stating the specified PMU can't be found. For >example, a format attr with 'config3:0-63' causes an error if config3 is >unknown to perf. This causes a compatibility issue between a newer >kernel and an older perf tool. > >The addition here makes any attr string up to the ':' ignored, but >still checks the 'bits' portion.
So, can you please show what is the behavior of the tool, with an actual command line and it's output, before and after your patch?
- Arnaldo
> >Signed-off-by: Rob Herring <robh@kernel.org> >--- >This is the YACC mud I threw and seems to stick. Maybe there's a better >way to handle this. It doesn't seem like there's a way to do wildcards >(i.e. config.*) in YACC. > >This is needed for this series[1]. Unfortunately the best we do to avoid >the issue is applying this to stable. I think there's some time before >v8.7 h/w is deployed, too. > >Rob > >[1] https://lore.kernel.org/all/20220825-arm-spe-v8-7-v1-0-c75b8d92e692@kernel.org/ > > tools/perf/util/pmu.y | 3 +++ > 1 file changed, 3 insertions(+) > >diff --git a/tools/perf/util/pmu.y b/tools/perf/util/pmu.y >index bfd7e8509869..3096864ec9b9 100644 >--- a/tools/perf/util/pmu.y >+++ b/tools/perf/util/pmu.y >@@ -60,6 +60,9 @@ PP_CONFIG2 ':' bits > PERF_PMU_FORMAT_VALUE_CONFIG2, > $3)); > } >+| >+error ':' bits >+{} > > bits: > bits ',' bit_term
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