perf tools: Warn about missing libelf

Commit-ID:  d30ff29562ecbf79e82df72724d0c6180f2e2c06
Gitweb:     http://git.kernel.org/tip/d30ff29562ecbf79e82df72724d0c6180f2e2c06
Author:     Namhyung Kim <[email protected]>
AuthorDate: Tue, 30 Oct 2012 00:06:46 +0900
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 31 Oct 2012 12:17:48 -0200

perf tools: Warn about missing libelf

When perf detects no libelf during the build, it'll use internal mini elf parser instead of libelf. But as it only supports minimal functionalities, it also disables support to 'probe' builtin command.

Currently it didn't warned to user. Fix it.

$ sudo apt-get remove libelf-dev
$ make
    CHK -fstack-protector-all
    CHK -Wstack-protector
    CHK -Wvolatile-register-var
    CHK bionic
    CHK libelf
    CHK glibc
Makefile:491: No libelf found, disables 'probe' tool, please install elfutils-libelf-devel/libelf-dev
    CHK libunwind
    CHK libaudit

$ make NO_LIBELF=1
    CHK -fstack-protector-all
    CHK -Wstack-protector
    CHK -Wvolatile-register-var
    CHK bionic
    CHK libaudit

---
 tools/perf/Makefile |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

index 7e25f59..b1801e0 100644
@@ -490,6 +490,8 @@ ifneq ($(call try-cc,$(SOURCE_LIBELF),$(FLAGS_LIBELF),libelf),y)
 		LIBC_SUPPORT := 1
 	endif
 	ifeq ($(LIBC_SUPPORT),1)
+		msg := $(warning No libelf found, disables 'probe' tool, please install elfutils-libelf-devel/libelf-dev);
+
 		NO_LIBELF := 1
 		NO_DWARF := 1
 		NO_DEMANGLE := 1