perf build: Add missing comment about NO_LIBTRACEEVENT=1

By default perf will fail the build if the development files for
libtraceevent are not available.

To build perf without libtraceevent support, disabling several features
such as 'perf trace', one needs to add NO_LIBTRACEVENT=1 to the make
command line.

Add the missing comments about that to the tools/perf/Makefile.perf
file, just like all the other such command line toggles.

Fixes: 378ef0f5d9d7f465 ("perf build: Use libtraceevent from the system")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/ZR6+MhXtLnv6ow6E@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 98604e396ac33643a74c50781ff3804625efddb0..456872ac410df4c0f8dbc41e345018d86f97c83c 100644 (file)
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -69,6 +69,10 @@ include ../scripts/utilities.mak
 # Define NO_LIBDW_DWARF_UNWIND if you do not want libdw support
 # for dwarf backtrace post unwind.
 #
+# Define NO_LIBTRACEEVENT=1 if you don't want libtraceevent to be linked,
+# this will remove multiple features and tools, such as 'perf trace',
+# that need it to read tracefs event format files, etc.
+#
 # Define NO_PERF_READ_VDSO32 if you do not want to build perf-read-vdso32
 # for reading the 32-bit compatibility VDSO in 64-bit mode
 #