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 <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 1 insertions, 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;
 			}