--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zPreMappedMemory.cpp	2018-06-08 19:46:33.747308585 +0200
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2016, 2017, 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.
+ *
+ * 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.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zPage.inline.hpp"
+#include "gc/z/zPhysicalMemory.inline.hpp"
+#include "gc/z/zPreMappedMemory.inline.hpp"
+#include "gc/z/zVirtualMemory.inline.hpp"
+#include "logging/log.hpp"
+
+ZPreMappedMemory::ZPreMappedMemory(ZVirtualMemoryManager &vmm, ZPhysicalMemoryManager &pmm, size_t size) :
+    _vmem(),
+    _pmem(),
+    _initialized(false) {
+  if (!vmm.is_initialized() || !pmm.is_initialized()) {
+    // Not initialized
+    return;
+  }
+
+  // Pre-mapping and pre-touching memory can take a long time. Log a message
+  // to help the user understand why the JVM might seem slow to start.
+  log_info(gc, init)("Pre-touching: %s", AlwaysPreTouch ? "Enabled" : "Disabled");
+  log_info(gc, init)("Pre-mapping: " SIZE_FORMAT "M", size / M);
+
+  _pmem = pmm.alloc(size);
+  if (_pmem.is_null()) {
+    // Out of memory
+    return;
+  }
+
+  _vmem = vmm.alloc(size, true /* alloc_from_front */);
+  if (_vmem.is_null()) {
+    // Out of address space
+    pmm.free(_pmem);
+    return;
+  }
+
+  // Map physical memory
+  pmm.map(_pmem, _vmem.start());
+
+  _initialized = true;
+}
+
+ZPage* ZPreMappedMemory::alloc_page(uint8_t type, size_t size) {
+  if (size > available()) {
+    // Not enough pre-mapped memory
+    return NULL;
+  }
+
+  // Take a chunk of the pre-mapped memory
+  const ZPhysicalMemory pmem = _pmem.split(size);
+  const ZVirtualMemory  vmem = _vmem.split(size);
+
+  ZPage* const page = new ZPage(type, vmem, pmem);
+  page->set_pre_mapped();
+
+  return page;
+}
+
+void ZPreMappedMemory::clear() {
+  assert(_pmem.is_null(), "Should be detached");
+  _vmem.clear();
+}