--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/test/jdk/jdk/jfr/jvm/TestLogImplementation.java	2018-04-09 19:00:18.766952119 +0200
@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jfr.jvm;
+
+import jdk.jfr.internal.JVM;
+import jdk.jfr.internal.Logger;
+import jdk.jfr.internal.LogTag;
+import jdk.jfr.internal.LogLevel;
+
+/*
+ * @test TestLogImplementation
+ * @key jfr
+ * @library /test/lib
+ * @modules jdk.jfr/jdk.jfr.internal
+ * @run main/othervm jdk.jfr.jvm.TestLogImplementation
+ */
+public class TestLogImplementation {
+    private static LogLevel DEFAULT_TEST_LOG_LEVEL = LogLevel.ERROR;
+    private static LogTag JFR_LOG_TAG = LogTag.JFR;
+
+    private static void assertAllLevelsForTag(LogTag tag, String message) {
+        for (LogLevel level : LogLevel.values()) {
+            Logger.log(tag, level, message);
+        }
+    }
+
+    private static void assertAllTagsForLevel(LogLevel level, String message) {
+        for (LogTag tag : LogTag.values()) {
+            Logger.log(tag, level, message);
+        }
+    }
+
+    public static void main(String... args) {
+        assertEmptyMessageOK();
+        assertNullMessageOK();
+        assertAllCharsOK();
+        assertLargeMessageOK();
+        assertFormatSpecifierOK();
+        assertAllLevelOK();
+        assertLogLevelUnderflow();
+        assertLogLevelOverflow();
+        assertLogTagUnderflow();
+        assertLogTagOverflow();
+    }
+
+    private static void assertAllLevelOK() {
+        assertAllLevelsForTag(JFR_LOG_TAG, "");
+        assertAllTagsForLevel(DEFAULT_TEST_LOG_LEVEL, "");
+    }
+
+    private static void assertFormatSpecifierOK() {
+        assertAllTagsForLevel(DEFAULT_TEST_LOG_LEVEL, "%s");
+        assertAllTagsForLevel(DEFAULT_TEST_LOG_LEVEL, "%n");
+        assertAllTagsForLevel(DEFAULT_TEST_LOG_LEVEL, "%h");
+    }
+
+    private static void assertLargeMessageOK() {
+        StringBuilder large = new StringBuilder();
+        for (int i = 0; i < 1000 * 1000; i++) {
+            large.append('o');
+        }
+        Logger.log(JFR_LOG_TAG, DEFAULT_TEST_LOG_LEVEL, large.toString());
+    }
+
+    private static void assertAllCharsOK() {
+        char c = Character.MIN_VALUE;
+        StringBuilder large = new StringBuilder();
+        int logSize = 0;
+        for(int i = Character.MIN_VALUE; i< (int)Character.MAX_VALUE; i++, c++) {
+            large.append(c);
+            logSize++;
+            if (logSize == 80) {
+                Logger.log(JFR_LOG_TAG, DEFAULT_TEST_LOG_LEVEL, large.toString());
+                large = new StringBuilder();
+            }
+        }
+    }
+
+    private static void assertEmptyMessageOK() {
+        assertAllLevelsForTag(JFR_LOG_TAG, "");
+    }
+
+    private static void assertNullMessageOK() {
+        assertAllLevelsForTag(JFR_LOG_TAG, (String)null);
+    }
+
+    private static void assertLogLevelUnderflow() {
+        try {
+            JVM.log(JFR_LOG_TAG.ordinal(), 0, (String)null);
+        } catch (IllegalArgumentException ex) {
+            // Expected
+        }
+    }
+
+    private static void assertLogLevelOverflow() {
+        try {
+            JVM.log(JFR_LOG_TAG.ordinal(), LogLevel.ERROR.ordinal() + 1, (String)null);
+        } catch (IllegalArgumentException ex) {
+            // Expected
+        }
+    }
+
+    private static void assertLogTagUnderflow() {
+        try {
+            JVM.log(JFR_LOG_TAG.ordinal() - 1, DEFAULT_TEST_LOG_LEVEL.ordinal(), (String)null);
+        } catch (IllegalArgumentException ex) {
+            // Expected
+        }
+    }
+
+    // since the enum will grow with new entries, provoking an overflow is problematic
+    // is there a built-in "current max" in a Java enum
+    private static void assertLogTagOverflow() {
+        try {
+            JVM.log(10000, DEFAULT_TEST_LOG_LEVEL.ordinal(), (String)null);
+        } catch (IllegalArgumentException ex) {
+            // Expected
+        }
+    }
+}