Messages in this thread | | | From | Rob Herring <> | Date | Thu, 1 Sep 2022 14:28:39 -0500 | Subject | Re: [PATCH] perf: Ignore format attributes with an unknown perf_event_attr field |
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On Thu, Sep 1, 2022 at 2:22 PM Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote: > > > > 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?
Before this patch with a kernel adding 'config3' I get:
# perf record -e arm_spe// -- true event syntax error: 'arm_spe//' \___ Cannot find PMU `arm_spe'. Missing kernel support? Run 'perf list' for a list of valid events
Usage: perf record [<options>] [<command>] or: perf record [<options>] -- <command> [<options>]
-e, --event <event> event selector. use 'perf list' to list available events
After this patch, I get:
# perf record -e arm_spe// -- true [ perf record: Woken up 2 times to write data ] [ perf record: Captured and wrote 0.091 MB perf.data ]
Rob
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