--- /dev/null	2018-06-17 23:18:20.806999507 +0800
+++ new/src/share/classes/jdk/jfr/internal/JVMSupport.java	2019-01-29 10:59:31.415797593 +0800
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2016, 2019, 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.internal;
+
+import java.io.IOException;
+
+/**
+ * Checks if the running VM supports Flight Recorder.
+ *
+ * Purpose of this helper class is to detect early and cleanly if the VM has
+ * support for Flight Recorder, i.e. not throw {@link UnsatisfiedLinkError} in
+ * unexpected places.
+ * <p>
+ * This is needed so a disabled-jfr.jar can be built for non Oracle JDKs.
+ */
+public final class JVMSupport {
+
+    private static final String UNSUPPORTED_VM_MESSAGE = "Flight Recorder is not supported on this VM";
+    private static final boolean notAvailable = !checkAvailability();
+
+    private static boolean checkAvailability() {
+        // set jfr.unsupported.vm to true to test API on an unsupported VM
+        try {
+            if (SecuritySupport.getBooleanProperty("jfr.unsupported.vm")) {
+                return false;
+            }
+        } catch (NoClassDefFoundError cnfe) {
+            // May happen on JDK 8, where sun.misc.Unsafe can't be found
+            return false;
+        }
+        try {
+            // Will typically throw UnsatisfiedLinkError if
+            // there is no native implementation
+            JVM.getJVM().isAvailable();
+            return true;
+        } catch (Throwable t) {
+            return false;
+        }
+    }
+
+    public static void ensureWithInternalError() {
+        if (notAvailable) {
+            throw new InternalError(UNSUPPORTED_VM_MESSAGE);
+        }
+    }
+
+    public static void ensureWithIOException() throws IOException {
+        if (notAvailable) {
+            throw new IOException(UNSUPPORTED_VM_MESSAGE);
+        }
+    }
+
+    public static void ensureWithIllegalStateException() {
+        if (notAvailable) {
+            throw new IllegalStateException(UNSUPPORTED_VM_MESSAGE);
+        }
+    }
+
+    public static boolean isNotAvailable() {
+        return notAvailable;
+    }
+}