--- a/make/autoconf/boot-jdk.m4	Thu Nov 30 16:26:23 2017 +0100
+++ b/make/autoconf/boot-jdk.m4	Thu Nov 30 16:27:31 2017 +0100
@@ -354,7 +354,7 @@
   AC_MSG_CHECKING([flags for boot jdk java command] )
 
   # Disable special log output when a debug build is used as Boot JDK...
-  ADD_JVM_ARG_IF_OK([-XX:-PrintVMOptions -XX:-UnlockDiagnosticVMOptions -XX:-LogVMOutput],boot_jdk_jvmargs,[$JAVA])
+  ADD_JVM_ARG_IF_OK([-XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput],boot_jdk_jvmargs,[$JAVA])
 
   # Force en-US environment
   ADD_JVM_ARG_IF_OK([-Duser.language=en -Duser.country=US],boot_jdk_jvmargs,[$JAVA])

--- a/make/autoconf/generated-configure.sh	Thu Nov 30 16:26:23 2017 +0100
+++ b/make/autoconf/generated-configure.sh	Thu Nov 30 16:27:31 2017 +0100
@@ -5155,7 +5155,7 @@
 #CUSTOM_AUTOCONF_INCLUDE
 
 # Do not change or remove the following line, it is needed for consistency checks:
-DATE_WHEN_GENERATED=1511359342
+DATE_WHEN_GENERATED=1512055625
 
 ###############################################################################
 #
@@ -66418,13 +66418,13 @@
 
   # Disable special log output when a debug build is used as Boot JDK...
 
-  $ECHO "Check if jvm arg is ok: -XX:-PrintVMOptions -XX:-UnlockDiagnosticVMOptions -XX:-LogVMOutput" >&5
-  $ECHO "Command: $JAVA -XX:-PrintVMOptions -XX:-UnlockDiagnosticVMOptions -XX:-LogVMOutput -version" >&5
-  OUTPUT=`$JAVA -XX:-PrintVMOptions -XX:-UnlockDiagnosticVMOptions -XX:-LogVMOutput -version 2>&1`
+  $ECHO "Check if jvm arg is ok: -XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput" >&5
+  $ECHO "Command: $JAVA -XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput -version" >&5
+  OUTPUT=`$JAVA -XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput -version 2>&1`
   FOUND_WARN=`$ECHO "$OUTPUT" | $GREP -i warn`
   FOUND_VERSION=`$ECHO $OUTPUT | $GREP " version \""`
   if test "x$FOUND_VERSION" != x && test "x$FOUND_WARN" = x; then
-    boot_jdk_jvmargs="$boot_jdk_jvmargs -XX:-PrintVMOptions -XX:-UnlockDiagnosticVMOptions -XX:-LogVMOutput"
+    boot_jdk_jvmargs="$boot_jdk_jvmargs -XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput"
     JVM_ARG_OK=true
   else
     $ECHO "Arg failed:" >&5