[tip:perf/core] perf parse-regs: Improve error output when faced with unknown register name

[tip-bot for Arnaldo Carvalho de Melo <tipbot@xxxxxxxxx>]

Commit-ID:  4c1cf20334ae6e390e1ea787ef76c40a161370d1
Gitweb:     https://git.kernel.org/tip/4c1cf20334ae6e390e1ea787ef76c40a161370d1
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Mon, 13 May 2019 14:28:32 -0400
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 15 May 2019 16:36:47 -0300

perf parse-regs: Improve error output when faced with unknown register name

Add quotes around the register name and suggest using 'perf record -I?'
to get the list of available registers.

Before:

  # perf record -Idi,xmm20,xmm1
  Warning:
  unknown register xmm20, check man page

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -I, --intr-regs[=<any register>]
                            sample selected machine registers on interrupt, use -I ? to list register names
  #
  # perf record -Idi,xmm20,xmm1
  Warning:
  unknown register "xmm20", check man page or run "perf record -I?"

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -I, --intr-regs[=<any register>]
                            sample selected machine registers on interrupt, use -I ? to list register names
  #

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-9a9hyuum8c0oggg86xd3sxc5@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/parse-regs-options.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-regs-options.c b/tools/perf/util/parse-regs-options.c
index e6599e290f46..9cb187a20fe2 100644
--- a/tools/perf/util/parse-regs-options.c
+++ b/tools/perf/util/parse-regs-options.c
@@ -48,8 +48,7 @@ parse_regs(const struct option *opt, const char *str, int unset)
 					break;
 			}
 			if (!r->name) {
-				ui__warning("unknown register %s,"
-					    " check man page\n", s);
+				ui__warning("Unknown register \"%s\", check man page or run \"perf record -I?\"\n", s);
 				goto error;
 			}