[tip:perf/core] perf jvmti: improve error message in Makefile

[tip-bot for Stephane Eranian <tipbot@zytor.com>]

Commit-ID:  7e9551bc72201838ebaf388224ff43ddf2b0d853
Gitweb:     http://git.kernel.org/tip/7e9551bc72201838ebaf388224ff43ddf2b0d853
Author:     Stephane Eranian <eranian@google.com>
AuthorDate: Thu, 25 Feb 2016 06:27:36 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 25 Feb 2016 10:43:28 -0300

perf jvmti: improve error message in Makefile

This patch improves the error message given by jvmti Makefile when the
alternatives command cannot be found. It now suggests the user locates
the root of their Java installation and pass it with JDIR=

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1456378056-18812-1-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/jvmti/Makefile | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/tools/perf/jvmti/Makefile b/tools/perf/jvmti/Makefile
index 0277a64..5ce61a1 100644
--- a/tools/perf/jvmti/Makefile
+++ b/tools/perf/jvmti/Makefile
@@ -35,12 +35,21 @@ SOLIBEXT=so
 
 # The following works at least on fedora 23, you may need the next
 # line for other distros.
-ifeq (,$(wildcard /usr/sbin/update-java-alternatives))
-JDIR=$(shell alternatives --display java | tail -1 | cut -d' ' -f 5 | sed 's%/jre/bin/java.%%g')
-else
+ifneq (,$(wildcard /usr/sbin/update-java-alternatives))
 JDIR=$(shell /usr/sbin/update-java-alternatives -l | head -1 | cut -d ' ' -f 3)
+else
+  ifneq (,$(wildcard /usr/sbin/alternatives))
+    JDIR=$(shell alternatives --display java | tail -1 | cut -d' ' -f 5 | sed 's%/jre/bin/java.%%g')
+  endif
 endif
-
+ifndef JDIR
+$(error Could not find alternatives command, you need to set JDIR= to point to the root of your Java directory)
+else
+  ifeq (,$(wildcard $(JDIR)/include/jvmti.h))
+  $(error the openjdk development package appears to me missing, install and try again)
+  endif
+endif
+$(info Using Java from $(JDIR))
 # -lrt required in 32-bit mode for clock_gettime()
 LIBS=-lelf -lrt
 INCDIR=-I $(JDIR)/include -I $(JDIR)/include/linux