diff a/src/hotspot/share/gc/shenandoah/shenandoahCardTable.cpp b/src/hotspot/share/gc/shenandoah/shenandoahCardTable.cpp
--- /dev/null
+++ b/src/hotspot/share/gc/shenandoah/shenandoahCardTable.cpp
@@ -0,0 +1,105 @@
+/*
+ * Copyright Amazon.com Inc. 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/shenandoah/shenandoahCardTable.hpp"
+#include "gc/shenandoah/shenandoahHeap.inline.hpp"
+#include "gc/shenandoah/shenandoahUtils.hpp"
+#include "runtime/init.hpp"
+#include "services/memTracker.hpp"
+
+void ShenandoahCardTable::initialize() {
+  size_t num_cards = cards_required(_whole_heap.word_size());
+
+  // each card takes 1 byte; + 1 for the guard card
+  size_t num_bytes = num_cards + 1;
+  const size_t granularity = os::vm_allocation_granularity();
+  _byte_map_size = align_up(num_bytes, MAX2(_page_size, granularity));
+
+  HeapWord* low_bound  = _whole_heap.start();
+  HeapWord* high_bound = _whole_heap.end();
+
+  // ReservedSpace constructor would assert rs_align >= os::vm_page_size().
+  const size_t rs_align = _page_size == os::vm_page_size() ? 0 : MAX2(_page_size, granularity);
+
+  ReservedSpace write_space(_byte_map_size, rs_align, _page_size);
+  initialize(write_space);
+
+  // The assembler store_check code will do an unsigned shift of the oop,
+  // then add it to _byte_map_base, i.e.
+  //
+  //   _byte_map = _byte_map_base + (uintptr_t(low_bound) >> card_shift)
+  _byte_map = (CardValue*) write_space.base();
+  _byte_map_base = _byte_map - (uintptr_t(low_bound) >> _card_shift);
+  assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
+  assert(byte_for(high_bound-1) <= &_byte_map[last_valid_index()], "Checking end of map");
+
+  _write_byte_map = _byte_map;
+  _write_byte_map_base = _byte_map_base;
+
+  ReservedSpace read_space(_byte_map_size, rs_align, _page_size);
+  initialize(read_space);
+
+  _read_byte_map = (CardValue*) read_space.base();
+  _read_byte_map_base = _read_byte_map - (uintptr_t(low_bound) >> card_shift());
+  assert(read_byte_for(low_bound) == &_read_byte_map[0], "Checking start of map");
+  assert(read_byte_for(high_bound-1) <= &_read_byte_map[last_valid_index()], "Checking end of map");
+
+  _covered[0] = _whole_heap;
+
+  log_trace(gc, barrier)("ShenandoahCardTable::ShenandoahCardTable:");
+  log_trace(gc, barrier)("    &_write_byte_map[0]: " INTPTR_FORMAT "  &_write_byte_map[_last_valid_index]: " INTPTR_FORMAT,
+                         p2i(&_write_byte_map[0]), p2i(&_write_byte_map[last_valid_index()]));
+  log_trace(gc, barrier)("    _write_byte_map_base: " INTPTR_FORMAT, p2i(_write_byte_map_base));
+  log_trace(gc, barrier)("    &_read_byte_map[0]: " INTPTR_FORMAT "  &_read_byte_map[_last_valid_index]: " INTPTR_FORMAT,
+                  p2i(&_read_byte_map[0]), p2i(&_read_byte_map[last_valid_index()]));
+  log_trace(gc, barrier)("    _read_byte_map_base: " INTPTR_FORMAT, p2i(_read_byte_map_base));
+}
+
+void ShenandoahCardTable::initialize(const ReservedSpace& card_table) {
+  MemTracker::record_virtual_memory_type((address)card_table.base(), mtGC);
+
+  os::trace_page_sizes("Card Table", _byte_map_size, _byte_map_size,
+                       _page_size, card_table.base(), card_table.size());
+  if (!card_table.is_reserved()) {
+    vm_exit_during_initialization("Could not reserve enough space for the card marking array");
+  }
+  os::commit_memory_or_exit(card_table.base(), _byte_map_size, card_table.alignment(), false,
+                            "Cannot commit memory for card table");
+}
+
+bool ShenandoahCardTable::is_in_young(const void* obj) const {
+  return ShenandoahHeap::heap()->is_in_young(obj);
+}
+
+CardValue* ShenandoahCardTable::read_byte_for(const void* p) {
+    CardValue* result = &_read_byte_map_base[uintptr_t(p) >> _card_shift];
+    assert(result >= _read_byte_map && result < _read_byte_map + _byte_map_size,
+           "out of bounds accessor for card marking array");
+    return result;
+}
+
+size_t ShenandoahCardTable::last_valid_index() {
+  return CardTable::last_valid_index();
+}
