Re: [PATCH] perf debug: List available options when no variable is specified

[Yang Jihong]

Hello,

On 2023/10/31 23:42, Arnaldo Carvalho de Melo wrote:
> Em Tue, Oct 31, 2023 at 08:08:23AM +0000, Yang Jihong escreveu:
> > Before:
>   
> >    # perf --debug
> >    No variable specified for --debug.
>   
> > After:
>   
> >    # perf --debug
> >    No variable specified for --debug, available options: verbose,ordered-events,stderr,data-convert,perf-event-open.
>
> Looks useful, but the implementation can be different to reduce
> maintainership costs, see below:
>
> > +++ b/tools/perf/perf.c
> > @@ -279,7 +279,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
> >   		} else if (!strcmp(cmd, "--debug")) {
> >   			if (*argc < 2) {
> > -				fprintf(stderr, "No variable specified for --debug.\n");
> > +				fprintf(stderr,
> > +					"No variable specified for --debug, available options: %s.\n",
> > +					perf_debug_options_string);
> >   				usage(perf_usage_string);
>
> > +++ b/tools/perf/util/debug.c
> > @@ -215,6 +215,9 @@ void trace_event(union perf_event *event)
> >   		     trace_event_printer, event);
> >   }
> >   
> > +const char perf_debug_options_string[] =
> > +	"verbose,ordered-events,stderr,data-convert,perf-event-open";
>
> Instead of adding a new variable that has to be kept in sync with
> debug_opts[], you could provide a function that iterates debug_opts,
> printing its options names, then use that function on perf.c handle_options.

Thanks for the advice.
OK, will send a v2 patch according to this scheme.

Thanks,
Yang