Em Tue, Nov 27, 2018 at 10:43:36AM +0200, Adrian Hunter escreveu:
> Users should never use 'pt=0', but if they do it may give a meaningless
> error:
>
> $ perf record -e intel_pt/pt=0/u uname
> Error:
> The sys_perf_event_open() syscall returned with 22 (Invalid argument)
> for
> event (intel_pt/pt=0/u).
>
> Fix that by forcing 'pt=1'.
>
> Signed-off-by: Adrian Hunter <[email protected]>
> ---
> tools/perf/arch/x86/util/intel-pt.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/tools/perf/arch/x86/util/intel-pt.c
> b/tools/perf/arch/x86/util/intel-pt.c
> index db0ba8caf5a2..af25a7824ee0 100644
> --- a/tools/perf/arch/x86/util/intel-pt.c
> +++ b/tools/perf/arch/x86/util/intel-pt.c
> @@ -524,10 +524,18 @@ static int intel_pt_validate_config(struct perf_pmu
> *intel_pt_pmu,
> struct perf_evsel *evsel)
> {
> int err;
> + char c;
>
> if (!evsel)
> return 0;
>
> + /*
> + * If supported, force pass-through config term (pt=1) even if user
> + * sets pt=0, which avoids senseless kernel errors.
> + */
> + if (perf_pmu__scan_file(intel_pt_pmu, "format/pt", "%c", &c) == 1)
> + evsel->attr.config |= 1;
shouldn't we have a warning like:
pr_warning("pt=0 doesn't make sense, forcing pt=1")
Instead of silently doing something the user, mistakenly, did
explicitely?
- Arnaldo
> +
> err = intel_pt_val_config_term(intel_pt_pmu, "caps/cycle_thresholds",
> "cyc_thresh", "caps/psb_cyc",
> evsel->attr.config);
> --
> 2.17.1
--
- Arnaldo
