build: embed the mdb_v8.so into the binary

This builds and includes the mdb_v8.so in the binary of node so mdb
can be sure to always use the latest version

8 files changed, 5132 insertions, 0 deletions

diff --git a/configure b/configure
index abb907081..833de8d11 100755
--- a/configure
+++ b/configure
@@ -475,6 +475,13 @@ def configure_node(o):
     o['variables']['node_use_dtrace'] = 'false'
     o['variables']['node_use_systemtap'] = 'false'
 
+  # if we're on illumos based systems wrap the helper library into the
+  # executable
+  if flavor == 'solaris':
+    o['variables']['node_use_mdb'] = 'true'
+  else:
+    o['variables']['node_use_mdb'] = 'false'
+
   if options.no_ifaddrs:
     o['defines'] += ['SUNOS_NO_IFADDRS']
 
diff --git a/deps/mdb_v8/mdb_v8.c b/deps/mdb_v8/mdb_v8.c
new file mode 100644
index 000000000..5ebfb6576
--- /dev/null
+++ b/deps/mdb_v8/mdb_v8.c
@@ -0,0 +1,4117 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * mdb(1M) module for debugging the V8 JavaScript engine.  This implementation
+ * makes heavy use of metadata defined in the V8 binary for inspecting in-memory
+ * structures.  Canned configurations can be manually loaded for V8 binaries
+ * that predate this metadata.  See mdb_v8_cfg.c for details.
+ */
+
+/*
+ * We hard-code our MDB_API_VERSION to be 3 to allow this module to be
+ * compiled on systems with higher version numbers, but still allow the
+ * resulting binary object to be used on older systems.  (We do not make use
+ * of functionality present in versions later than 3.)  This is particularly
+ * important for mdb_v8 because (1) it's used in particular to debug
+ * application-level software and (2) it has a history of rapid evolution.
+ */
+#define	MDB_API_VERSION		3
+
+#include <sys/mdb_modapi.h>
+#include <assert.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <libproc.h>
+#include <sys/avl.h>
+#include <alloca.h>
+
+#include "v8dbg.h"
+#include "v8cfg.h"
+
+#define	offsetof(s, m)	((size_t)(&(((s *)0)->m)))
+
+/*
+ * The "v8_class" and "v8_field" structures describe the C++ classes used to
+ * represent V8 heap objects.
+ */
+typedef struct v8_class {
+	struct v8_class *v8c_next;	/* list linkage */
+	struct v8_class *v8c_parent;	/* parent class (inheritance) */
+	struct v8_field *v8c_fields;	/* array of class fields */
+	size_t		v8c_start;	/* offset of first class field */
+	size_t		v8c_end;	/* offset of first subclass field */
+	char		v8c_name[64];	/* heap object class name */
+} v8_class_t;
+
+typedef struct v8_field {
+	struct v8_field	*v8f_next;	/* list linkage */
+	ssize_t		v8f_offset;	/* field offset */
+	char 		v8f_name[64];	/* field name */
+	boolean_t	v8f_isbyte;	/* 1-byte int field */
+	boolean_t	v8f_isstr;	/* NUL-terminated string */
+} v8_field_t;
+
+/*
+ * Similarly, the "v8_enum" structure describes an enum from V8.
+ */
+typedef struct {
+	char 	v8e_name[64];
+	uint_t	v8e_value;
+} v8_enum_t;
+
+/*
+ * During configuration, the dmod updates these globals with the actual set of
+ * classes, types, and frame types based on the debug metadata.
+ */
+static v8_class_t	*v8_classes;
+
+static v8_enum_t	v8_types[128];
+static int 		v8_next_type;
+
+static v8_enum_t 	v8_frametypes[16];
+static int 		v8_next_frametype;
+
+static int		v8_silent;
+
+/*
+ * The following constants describe offsets from the frame pointer that are used
+ * to inspect each stack frame.  They're initialized from the debug metadata.
+ */
+static ssize_t	V8_OFF_FP_CONTEXT;
+static ssize_t	V8_OFF_FP_MARKER;
+static ssize_t	V8_OFF_FP_FUNCTION;
+static ssize_t	V8_OFF_FP_ARGS;
+
+/*
+ * The following constants are used by macros defined in heap-dbg-common.h to
+ * examine the types of various V8 heap objects.  In general, the macros should
+ * be preferred to using the constants directly.  The values of these constants
+ * are initialized from the debug metadata.
+ */
+static intptr_t	V8_FirstNonstringType;
+static intptr_t	V8_IsNotStringMask;
+static intptr_t	V8_StringTag;
+static intptr_t	V8_NotStringTag;
+static intptr_t	V8_StringEncodingMask;
+static intptr_t	V8_TwoByteStringTag;
+static intptr_t	V8_AsciiStringTag;
+static intptr_t	V8_StringRepresentationMask;
+static intptr_t	V8_SeqStringTag;
+static intptr_t	V8_ConsStringTag;
+static intptr_t	V8_ExternalStringTag;
+static intptr_t	V8_FailureTag;
+static intptr_t	V8_FailureTagMask;
+static intptr_t	V8_HeapObjectTag;
+static intptr_t	V8_HeapObjectTagMask;
+static intptr_t	V8_SmiTag;
+static intptr_t	V8_SmiTagMask;
+static intptr_t	V8_SmiValueShift;
+static intptr_t	V8_SmiShiftSize;
+static intptr_t	V8_PointerSizeLog2;
+
+static intptr_t	V8_ISSHARED_SHIFT;
+static intptr_t	V8_DICT_SHIFT;
+static intptr_t	V8_DICT_PREFIX_SIZE;
+static intptr_t	V8_DICT_ENTRY_SIZE;
+static intptr_t	V8_DICT_START_INDEX;
+static intptr_t	V8_PROP_IDX_CONTENT;
+static intptr_t	V8_PROP_IDX_FIRST;
+static intptr_t	V8_PROP_TYPE_FIELD;
+static intptr_t	V8_PROP_FIRST_PHANTOM;
+static intptr_t	V8_PROP_TYPE_MASK;
+static intptr_t	V8_PROP_DESC_KEY;
+static intptr_t	V8_PROP_DESC_DETAILS;
+static intptr_t	V8_PROP_DESC_VALUE;
+static intptr_t	V8_PROP_DESC_SIZE;
+static intptr_t	V8_TRANSITIONS_IDX_DESC;
+
+static intptr_t V8_TYPE_JSOBJECT = -1;
+static intptr_t V8_TYPE_JSARRAY = -1;
+static intptr_t V8_TYPE_FIXEDARRAY = -1;
+
+/*
+ * Although we have this information in v8_classes, the following offsets are
+ * defined explicitly because they're used directly in code below.
+ */
+static ssize_t V8_OFF_CODE_INSTRUCTION_SIZE;
+static ssize_t V8_OFF_CODE_INSTRUCTION_START;
+static ssize_t V8_OFF_CONSSTRING_FIRST;
+static ssize_t V8_OFF_CONSSTRING_SECOND;
+static ssize_t V8_OFF_EXTERNALSTRING_RESOURCE;
+static ssize_t V8_OFF_FIXEDARRAY_DATA;
+static ssize_t V8_OFF_FIXEDARRAY_LENGTH;
+static ssize_t V8_OFF_HEAPNUMBER_VALUE;
+static ssize_t V8_OFF_HEAPOBJECT_MAP;
+static ssize_t V8_OFF_JSARRAY_LENGTH;
+static ssize_t V8_OFF_JSDATE_VALUE;
+static ssize_t V8_OFF_JSFUNCTION_SHARED;
+static ssize_t V8_OFF_JSOBJECT_ELEMENTS;
+static ssize_t V8_OFF_JSOBJECT_PROPERTIES;
+static ssize_t V8_OFF_MAP_CONSTRUCTOR;
+static ssize_t V8_OFF_MAP_INOBJECT_PROPERTIES;
+static ssize_t V8_OFF_MAP_INSTANCE_ATTRIBUTES;
+static ssize_t V8_OFF_MAP_INSTANCE_DESCRIPTORS;
+static ssize_t V8_OFF_MAP_INSTANCE_SIZE;
+static ssize_t V8_OFF_MAP_BIT_FIELD3;
+static ssize_t V8_OFF_MAP_TRANSITIONS;
+static ssize_t V8_OFF_ODDBALL_TO_STRING;
+static ssize_t V8_OFF_SCRIPT_LINE_ENDS;
+static ssize_t V8_OFF_SCRIPT_NAME;
+static ssize_t V8_OFF_SEQASCIISTR_CHARS;
+static ssize_t V8_OFF_SEQONEBYTESTR_CHARS;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_CODE;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_FUNCTION_TOKEN_POSITION;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_INFERRED_NAME;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_LENGTH;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_SCRIPT;
+static ssize_t V8_OFF_SHAREDFUNCTIONINFO_NAME;
+static ssize_t V8_OFF_STRING_LENGTH;
+
+#define	NODE_OFF_EXTSTR_DATA		0x4	/* see node_string.h */
+
+#define	V8_CONSTANT_OPTIONAL		1
+#define	V8_CONSTANT_HASFALLBACK		2
+
+#define	V8_CONSTANT_MAJORSHIFT		3
+#define	V8_CONSTANT_MAJORMASK		((1 << 4) - 1)
+#define	V8_CONSTANT_MAJOR(flags)	\
+	(((flags) >> V8_CONSTANT_MAJORSHIFT) & V8_CONSTANT_MAJORMASK)
+
+#define	V8_CONSTANT_MINORSHIFT		7
+#define	V8_CONSTANT_MINORMASK		((1 << 9) - 1)
+#define	V8_CONSTANT_MINOR(flags)	\
+	(((flags) >> V8_CONSTANT_MINORSHIFT) & V8_CONSTANT_MINORMASK)
+
+#define	V8_CONSTANT_FALLBACK(maj, min) \
+	(V8_CONSTANT_OPTIONAL | V8_CONSTANT_HASFALLBACK | \
+	((maj) << V8_CONSTANT_MAJORSHIFT) | ((min) << V8_CONSTANT_MINORSHIFT))
+
+/*
+ * Table of constants used directly by this file.
+ */
+typedef struct v8_constant {
+	intptr_t	*v8c_valp;
+	const char	*v8c_symbol;
+	uint32_t	v8c_flags;
+	intptr_t	v8c_fallback;
+} v8_constant_t;
+
+static v8_constant_t v8_constants[] = {
+	{ &V8_OFF_FP_CONTEXT,		"v8dbg_off_fp_context"		},
+	{ &V8_OFF_FP_FUNCTION,		"v8dbg_off_fp_function"		},
+	{ &V8_OFF_FP_MARKER,		"v8dbg_off_fp_marker"		},
+	{ &V8_OFF_FP_ARGS,		"v8dbg_off_fp_args"		},
+
+	{ &V8_FirstNonstringType,	"v8dbg_FirstNonstringType"	},
+	{ &V8_IsNotStringMask,		"v8dbg_IsNotStringMask"		},
+	{ &V8_StringTag,		"v8dbg_StringTag"		},
+	{ &V8_NotStringTag,		"v8dbg_NotStringTag"		},
+	{ &V8_StringEncodingMask,	"v8dbg_StringEncodingMask"	},
+	{ &V8_TwoByteStringTag,		"v8dbg_TwoByteStringTag"	},
+	{ &V8_AsciiStringTag,		"v8dbg_AsciiStringTag"		},
+	{ &V8_StringRepresentationMask,	"v8dbg_StringRepresentationMask" },
+	{ &V8_SeqStringTag,		"v8dbg_SeqStringTag"		},
+	{ &V8_ConsStringTag,		"v8dbg_ConsStringTag"		},
+	{ &V8_ExternalStringTag,	"v8dbg_ExternalStringTag"	},
+	{ &V8_FailureTag,		"v8dbg_FailureTag"		},
+	{ &V8_FailureTagMask,		"v8dbg_FailureTagMask"		},
+	{ &V8_HeapObjectTag,		"v8dbg_HeapObjectTag"		},
+	{ &V8_HeapObjectTagMask,	"v8dbg_HeapObjectTagMask"	},
+	{ &V8_SmiTag,			"v8dbg_SmiTag"			},
+	{ &V8_SmiTagMask,		"v8dbg_SmiTagMask"		},
+	{ &V8_SmiValueShift,		"v8dbg_SmiValueShift"		},
+	{ &V8_SmiShiftSize,		"v8dbg_SmiShiftSize",
+#ifdef _LP64
+	    V8_CONSTANT_FALLBACK(0, 0), 31 },
+#else
+	    V8_CONSTANT_FALLBACK(0, 0), 0 },
+#endif
+	{ &V8_PointerSizeLog2,		"v8dbg_PointerSizeLog2"		},
+
+	{ &V8_DICT_SHIFT,		"v8dbg_dict_shift",
+	    V8_CONSTANT_FALLBACK(3, 13), 24 },
+	{ &V8_DICT_PREFIX_SIZE,		"v8dbg_dict_prefix_size",
+	    V8_CONSTANT_FALLBACK(3, 11), 2 },
+	{ &V8_DICT_ENTRY_SIZE,		"v8dbg_dict_entry_size",
+	    V8_CONSTANT_FALLBACK(3, 11), 3 },
+	{ &V8_DICT_START_INDEX,		"v8dbg_dict_start_index",
+	    V8_CONSTANT_FALLBACK(3, 11), 3 },
+	{ &V8_ISSHARED_SHIFT,		"v8dbg_isshared_shift",
+	    V8_CONSTANT_FALLBACK(3, 11), 0 },
+	{ &V8_PROP_IDX_FIRST,		"v8dbg_prop_idx_first"		},
+	{ &V8_PROP_TYPE_FIELD,		"v8dbg_prop_type_field"		},
+	{ &V8_PROP_FIRST_PHANTOM,	"v8dbg_prop_type_first_phantom"	},
+	{ &V8_PROP_TYPE_MASK,		"v8dbg_prop_type_mask"		},
+	{ &V8_PROP_IDX_CONTENT,		"v8dbg_prop_idx_content",
+	    V8_CONSTANT_OPTIONAL },
+	{ &V8_PROP_DESC_KEY,		"v8dbg_prop_desc_key",
+	    V8_CONSTANT_FALLBACK(0, 0), 0 },
+	{ &V8_PROP_DESC_DETAILS,	"v8dbg_prop_desc_details",
+	    V8_CONSTANT_FALLBACK(0, 0), 1 },
+	{ &V8_PROP_DESC_VALUE,		"v8dbg_prop_desc_value",
+	    V8_CONSTANT_FALLBACK(0, 0), 2 },
+	{ &V8_PROP_DESC_SIZE,		"v8dbg_prop_desc_size",
+	    V8_CONSTANT_FALLBACK(0, 0), 3 },
+	{ &V8_TRANSITIONS_IDX_DESC,	"v8dbg_transitions_idx_descriptors",
+	    V8_CONSTANT_OPTIONAL },
+};
+
+static int v8_nconstants = sizeof (v8_constants) / sizeof (v8_constants[0]);
+
+typedef struct v8_offset {
+	ssize_t		*v8o_valp;
+	const char	*v8o_class;
+	const char	*v8o_member;
+	boolean_t	v8o_optional;
+} v8_offset_t;
+
+static v8_offset_t v8_offsets[] = {
+	{ &V8_OFF_CODE_INSTRUCTION_SIZE,
+	    "Code", "instruction_size" },
+	{ &V8_OFF_CODE_INSTRUCTION_START,
+	    "Code", "instruction_start" },
+	{ &V8_OFF_CONSSTRING_FIRST,
+	    "ConsString", "first" },
+	{ &V8_OFF_CONSSTRING_SECOND,
+	    "ConsString", "second" },
+	{ &V8_OFF_EXTERNALSTRING_RESOURCE,
+	    "ExternalString", "resource" },
+	{ &V8_OFF_FIXEDARRAY_DATA,
+	    "FixedArray", "data" },
+	{ &V8_OFF_FIXEDARRAY_LENGTH,
+	    "FixedArray", "length" },
+	{ &V8_OFF_HEAPNUMBER_VALUE,
+	    "HeapNumber", "value" },
+	{ &V8_OFF_HEAPOBJECT_MAP,
+	    "HeapObject", "map" },
+	{ &V8_OFF_JSARRAY_LENGTH,
+	    "JSArray", "length" },
+	{ &V8_OFF_JSDATE_VALUE,
+	    "JSDate", "value", B_TRUE },
+	{ &V8_OFF_JSFUNCTION_SHARED,
+	    "JSFunction", "shared" },
+	{ &V8_OFF_JSOBJECT_ELEMENTS,
+	    "JSObject", "elements" },
+	{ &V8_OFF_JSOBJECT_PROPERTIES,
+	    "JSObject", "properties" },
+	{ &V8_OFF_MAP_CONSTRUCTOR,
+	    "Map", "constructor" },
+	{ &V8_OFF_MAP_INOBJECT_PROPERTIES,
+	    "Map", "inobject_properties" },
+	{ &V8_OFF_MAP_INSTANCE_ATTRIBUTES,
+	    "Map", "instance_attributes" },
+	{ &V8_OFF_MAP_INSTANCE_DESCRIPTORS,
+	    "Map", "instance_descriptors", B_TRUE },
+	{ &V8_OFF_MAP_TRANSITIONS,
+	    "Map", "transitions", B_TRUE },
+	{ &V8_OFF_MAP_INSTANCE_SIZE,
+	    "Map", "instance_size" },
+	{ &V8_OFF_MAP_BIT_FIELD3,
+	    "Map", "bit_field3", B_TRUE },
+	{ &V8_OFF_ODDBALL_TO_STRING,
+	    "Oddball", "to_string" },
+	{ &V8_OFF_SCRIPT_LINE_ENDS,
+	    "Script", "line_ends" },
+	{ &V8_OFF_SCRIPT_NAME,
+	    "Script", "name" },
+	{ &V8_OFF_SEQASCIISTR_CHARS,
+	    "SeqAsciiString", "chars", B_TRUE },
+	{ &V8_OFF_SEQONEBYTESTR_CHARS,
+	    "SeqOneByteString", "chars", B_TRUE },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_CODE,
+	    "SharedFunctionInfo", "code" },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_FUNCTION_TOKEN_POSITION,
+	    "SharedFunctionInfo", "function_token_position" },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_INFERRED_NAME,
+	    "SharedFunctionInfo", "inferred_name" },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_LENGTH,
+	    "SharedFunctionInfo", "length" },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_NAME,
+	    "SharedFunctionInfo", "name" },
+	{ &V8_OFF_SHAREDFUNCTIONINFO_SCRIPT,
+	    "SharedFunctionInfo", "script" },
+	{ &V8_OFF_STRING_LENGTH,
+	    "String", "length" },
+};
+
+static int v8_noffsets = sizeof (v8_offsets) / sizeof (v8_offsets[0]);
+
+static uintptr_t v8_major;
+static uintptr_t v8_minor;
+static uintptr_t v8_build;
+static uintptr_t v8_patch;
+
+static int autoconf_iter_symbol(mdb_symbol_t *, void *);
+static v8_class_t *conf_class_findcreate(const char *);
+static v8_field_t *conf_field_create(v8_class_t *, const char *, size_t);
+static char *conf_next_part(char *, char *);
+static int conf_update_parent(const char *);
+static int conf_update_field(v8_cfg_t *, const char *);
+static int conf_update_enum(v8_cfg_t *, const char *, const char *,
+    v8_enum_t *);
+static int conf_update_type(v8_cfg_t *, const char *);
+static int conf_update_frametype(v8_cfg_t *, const char *);
+static void conf_class_compute_offsets(v8_class_t *);
+
+static int read_typebyte(uint8_t *, uintptr_t);
+static int heap_offset(const char *, const char *, ssize_t *);
+
+/*
+ * Invoked when this dmod is initially loaded to load the set of classes, enums,
+ * and other constants from the metadata in the target binary.
+ */
+static int
+autoconfigure(v8_cfg_t *cfgp)
+{
+	v8_class_t *clp;
+	v8_enum_t *ep;
+	struct v8_constant *cnp;
+	int ii;
+	int failed = 0;
+
+	assert(v8_classes == NULL);
+
+	/*
+	 * Iterate all global symbols looking for metadata.
+	 */
+	if (cfgp->v8cfg_iter(cfgp, autoconf_iter_symbol, cfgp) != 0) {
+		mdb_warn("failed to autoconfigure V8 support\n");
+		return (-1);
+	}
+
+	/*
+	 * By now we've configured all of the classes so we can update the
+	 * "start" and "end" fields in each class with information from its
+	 * parent class.
+	 */
+	for (clp = v8_classes; clp != NULL; clp = clp->v8c_next) {
+		if (clp->v8c_end != (size_t)-1)
+			continue;
+
+		conf_class_compute_offsets(clp);
+	};
+
+	/*
+	 * Load various constants used directly in the module.
+	 */
+	for (ii = 0; ii < v8_nconstants; ii++) {
+		cnp = &v8_constants[ii];
+
+		if (cfgp->v8cfg_readsym(cfgp,
+		    cnp->v8c_symbol, cnp->v8c_valp) != -1) {
+			continue;
+		}
+
+		if (!(cnp->v8c_flags & V8_CONSTANT_OPTIONAL)) {
+			mdb_warn("failed to read \"%s\"", cnp->v8c_symbol);
+			failed++;
+			continue;
+		}
+
+		if (!(cnp->v8c_flags & V8_CONSTANT_HASFALLBACK) ||
+		    v8_major < V8_CONSTANT_MAJOR(cnp->v8c_flags) ||
+		    (v8_major == V8_CONSTANT_MAJOR(cnp->v8c_flags) &&
+		    v8_minor < V8_CONSTANT_MINOR(cnp->v8c_flags))) {
+			*cnp->v8c_valp = -1;
+			continue;
+		}
+
+		/*
+		 * We have a fallback -- and we know that the version satisfies
+		 * the fallback's version constraints; use the fallback value.
+		 */
+		*cnp->v8c_valp = cnp->v8c_fallback;
+	}
+
+	/*
+	 * Load type values for well-known classes that we use a lot.
+	 */
+	for (ep = v8_types; ep->v8e_name[0] != '\0'; ep++) {
+		if (strcmp(ep->v8e_name, "JSObject") == 0)
+			V8_TYPE_JSOBJECT = ep->v8e_value;
+
+		if (strcmp(ep->v8e_name, "JSArray") == 0)
+			V8_TYPE_JSARRAY = ep->v8e_value;
+
+		if (strcmp(ep->v8e_name, "FixedArray") == 0)
+			V8_TYPE_FIXEDARRAY = ep->v8e_value;
+	}
+
+	if (V8_TYPE_JSOBJECT == -1) {
+		mdb_warn("couldn't find JSObject type\n");
+		failed++;
+	}
+
+	if (V8_TYPE_JSARRAY == -1) {
+		mdb_warn("couldn't find JSArray type\n");
+		failed++;
+	}
+
+	if (V8_TYPE_FIXEDARRAY == -1) {
+		mdb_warn("couldn't find FixedArray type\n");
+		failed++;
+	}
+
+	/*
+	 * Finally, load various class offsets.
+	 */
+	for (ii = 0; ii < v8_noffsets; ii++) {
+		struct v8_offset *offp = &v8_offsets[ii];
+		const char *klass = offp->v8o_class;
+
+again:
+		if (heap_offset(klass, offp->v8o_member, offp->v8o_valp) == 0)
+			continue;
+
+		if (strcmp(klass, "FixedArray") == 0) {
+			/*
+			 * The V8 included in node v0.6 uses a FixedArrayBase
+			 * class to contain the "length" field, while the one
+			 * in v0.4 has no such base class and stores the field
+			 * directly in FixedArray; if we failed to derive
+			 * the offset from FixedArray, try FixedArrayBase.
+			 */
+			klass = "FixedArrayBase";
+			goto again;
+		}
+
+		if (offp->v8o_optional) {
+			*offp->v8o_valp = -1;
+			continue;
+		}
+
+		mdb_warn("couldn't find class \"%s\", field \"%s\"\n",
+		    offp->v8o_class, offp->v8o_member);
+		failed++;
+	}
+
+	if (!((V8_OFF_SEQASCIISTR_CHARS != -1) ^
+	    (V8_OFF_SEQONEBYTESTR_CHARS != -1))) {
+		mdb_warn("expected exactly one of SeqAsciiString and "
+		    "SeqOneByteString to be defined\n");
+		failed++;
+	}
+
+	if (V8_OFF_SEQONEBYTESTR_CHARS != -1)
+		V8_OFF_SEQASCIISTR_CHARS = V8_OFF_SEQONEBYTESTR_CHARS;
+
+	return (failed ? -1 : 0);
+}
+
+/* ARGSUSED */
+static int
+autoconf_iter_symbol(mdb_symbol_t *symp, void *arg)
+{
+	v8_cfg_t *cfgp = arg;
+
+	if (strncmp(symp->sym_name, "v8dbg_parent_",
+	    sizeof ("v8dbg_parent_") - 1) == 0)
+		return (conf_update_parent(symp->sym_name));
+
+	if (strncmp(symp->sym_name, "v8dbg_class_",
+	    sizeof ("v8dbg_class_") - 1) == 0)
+		return (conf_update_field(cfgp, symp->sym_name));
+
+	if (strncmp(symp->sym_name, "v8dbg_type_",
+	    sizeof ("v8dbg_type_") - 1) == 0)
+		return (conf_update_type(cfgp, symp->sym_name));
+
+	if (strncmp(symp->sym_name, "v8dbg_frametype_",
+	    sizeof ("v8dbg_frametype_") - 1) == 0)
+		return (conf_update_frametype(cfgp, symp->sym_name));
+
+	return (0);
+}
+
+/*
+ * Extracts the next field of a string whose fields are separated by "__" (as
+ * the V8 metadata symbols are).
+ */
+static char *
+conf_next_part(char *buf, char *start)
+{
+	char *pp;
+
+	if ((pp = strstr(start, "__")) == NULL) {
+		mdb_warn("malformed symbol name: %s\n", buf);
+		return (NULL);
+	}
+
+	*pp = '\0';
+	return (pp + sizeof ("__") - 1);
+}
+
+static v8_class_t *
+conf_class_findcreate(const char *name)
+{
+	v8_class_t *clp, *iclp, *prev = NULL;
+	int cmp;
+
+	for (iclp = v8_classes; iclp != NULL; iclp = iclp->v8c_next) {
+		if ((cmp = strcmp(iclp->v8c_name, name)) == 0)
+			return (iclp);
+
+		if (cmp > 0)
+			break;
+
+		prev = iclp;
+	}
+
+	if ((clp = mdb_zalloc(sizeof (*clp), UM_NOSLEEP)) == NULL)
+		return (NULL);
+
+	(void) strlcpy(clp->v8c_name, name, sizeof (clp->v8c_name));
+	clp->v8c_end = (size_t)-1;
+	clp->v8c_next = iclp;
+
+	if (prev != NULL) {
+		prev->v8c_next = clp;
+	} else {
+		v8_classes = clp;
+	}
+
+	return (clp);
+}
+
+static v8_field_t *
+conf_field_create(v8_class_t *clp, const char *name, size_t offset)
+{
+	v8_field_t *flp, *iflp;
+
+	if ((flp = mdb_zalloc(sizeof (*flp), UM_NOSLEEP)) == NULL)
+		return (NULL);
+
+	(void) strlcpy(flp->v8f_name, name, sizeof (flp->v8f_name));
+	flp->v8f_offset = offset;
+
+	if (clp->v8c_fields == NULL || clp->v8c_fields->v8f_offset > offset) {
+		flp->v8f_next = clp->v8c_fields;
+		clp->v8c_fields = flp;
+		return (flp);
+	}
+
+	for (iflp = clp->v8c_fields; iflp->v8f_next != NULL;
+	    iflp = iflp->v8f_next) {
+		if (iflp->v8f_next->v8f_offset > offset)
+			break;
+	}
+
+	flp->v8f_next = iflp->v8f_next;
+	iflp->v8f_next = flp;
+	return (flp);
+}
+
+/*
+ * Given a "v8dbg_parent_X__Y", symbol, update the parent of class X to class Y.
+ * Note that neither class necessarily exists already.
+ */
+static int
+conf_update_parent(const char *symbol)
+{
+	char *pp, *qq;
+	char buf[128];
+	v8_class_t *clp, *pclp;
+
+	(void) strlcpy(buf, symbol, sizeof (buf));
+	pp = buf + sizeof ("v8dbg_parent_") - 1;
+	qq = conf_next_part(buf, pp);
+
+	if (qq == NULL)
+		return (-1);
+
+	clp = conf_class_findcreate(pp);
+	pclp = conf_class_findcreate(qq);
+
+	if (clp == NULL || pclp == NULL) {
+		mdb_warn("mdb_v8: out of memory\n");
+		return (-1);
+	}
+
+	clp->v8c_parent = pclp;
+	return (0);
+}
+
+/*
+ * Given a "v8dbg_class_CLASS__FIELD__TYPE", symbol, save field "FIELD" into
+ * class CLASS with the offset described by the symbol.  Note that CLASS does
+ * not necessarily exist already.
+ */
+static int
+conf_update_field(v8_cfg_t *cfgp, const char *symbol)
+{
+	v8_class_t *clp;
+	v8_field_t *flp;
+	intptr_t offset;
+	char *pp, *qq, *tt;
+	char buf[128];
+
+	(void) strlcpy(buf, symbol, sizeof (buf));
+
+	pp = buf + sizeof ("v8dbg_class_") - 1;
+	qq = conf_next_part(buf, pp);
+
+	if (qq == NULL || (tt = conf_next_part(buf, qq)) == NULL)
+		return (-1);
+
+	if (cfgp->v8cfg_readsym(cfgp, symbol, &offset) == -1) {
+		mdb_warn("failed to read symbol \"%s\"", symbol);
+		return (-1);
+	}
+
+	if ((clp = conf_class_findcreate(pp)) == NULL ||
+	    (flp = conf_field_create(clp, qq, (size_t)offset)) == NULL)
+		return (-1);
+
+	if (strcmp(tt, "int") == 0)
+		flp->v8f_isbyte = B_TRUE;
+
+	if (strcmp(tt, "char") == 0)
+		flp->v8f_isstr = B_TRUE;
+
+	return (0);
+}
+
+static int
+conf_update_enum(v8_cfg_t *cfgp, const char *symbol, const char *name,
+    v8_enum_t *enp)
+{
+	intptr_t value;
+
+	if (cfgp->v8cfg_readsym(cfgp, symbol, &value) == -1) {
+		mdb_warn("failed to read symbol \"%s\"", symbol);
+		return (-1);
+	}
+
+	enp->v8e_value = (int)value;
+	(void) strlcpy(enp->v8e_name, name, sizeof (enp->v8e_name));
+	return (0);
+}
+
+/*
+ * Given a "v8dbg_type_TYPENAME" constant, save the type name in v8_types.  Note
+ * that this enum has multiple integer values with the same string label.
+ */
+static int
+conf_update_type(v8_cfg_t *cfgp, const char *symbol)
+{
+	char *klass;
+	v8_enum_t *enp;
+	char buf[128];
+
+	if (v8_next_type > sizeof (v8_types) / sizeof (v8_types[0])) {
+		mdb_warn("too many V8 types\n");
+		return (-1);
+	}
+
+	(void) strlcpy(buf, symbol, sizeof (buf));
+
+	klass = buf + sizeof ("v8dbg_type_") - 1;
+	if (conf_next_part(buf, klass) == NULL)
+		return (-1);
+
+	enp = &v8_types[v8_next_type++];
+	return (conf_update_enum(cfgp, symbol, klass, enp));
+}
+
+/*
+ * Given a "v8dbg_frametype_TYPENAME" constant, save the frame type in
+ * v8_frametypes.
+ */
+static int
+conf_update_frametype(v8_cfg_t *cfgp, const char *symbol)
+{
+	const char *frametype;
+	v8_enum_t *enp;
+
+	if (v8_next_frametype >
+	    sizeof (v8_frametypes) / sizeof (v8_frametypes[0])) {
+		mdb_warn("too many V8 frame types\n");
+		return (-1);
+	}
+
+	enp = &v8_frametypes[v8_next_frametype++];
+	frametype = symbol + sizeof ("v8dbg_frametype_") - 1;
+	return (conf_update_enum(cfgp, symbol, frametype, enp));
+}
+
+/*
+ * Now that all classes have been loaded, update the "start" and "end" fields of
+ * each class based on the values of its parent class.
+ */
+static void
+conf_class_compute_offsets(v8_class_t *clp)
+{
+	v8_field_t *flp;
+
+	assert(clp->v8c_start == 0);
+	assert(clp->v8c_end == (size_t)-1);
+
+	if (clp->v8c_parent != NULL) {
+		if (clp->v8c_parent->v8c_end == (size_t)-1)
+			conf_class_compute_offsets(clp->v8c_parent);
+
+		clp->v8c_start = clp->v8c_parent->v8c_end;
+	}
+
+	if (clp->v8c_fields == NULL) {
+		clp->v8c_end = clp->v8c_start;
+		return;
+	}
+
+	for (flp = clp->v8c_fields; flp->v8f_next != NULL; flp = flp->v8f_next)
+		;
+
+	if (flp == NULL)
+		clp->v8c_end = clp->v8c_start;
+	else
+		clp->v8c_end = flp->v8f_offset + sizeof (uintptr_t);
+}
+
+/*
+ * Utility functions
+ */
+#define	JSSTR_NONE		0
+#define	JSSTR_NUDE		JSSTR_NONE
+#define	JSSTR_VERBOSE		0x1
+#define	JSSTR_QUOTED		0x2
+
+static int jsstr_print(uintptr_t, uint_t, char **, size_t *);
+static boolean_t jsobj_is_undefined(uintptr_t addr);
+
+static const char *
+enum_lookup_str(v8_enum_t *enums, int val, const char *dflt)
+{
+	v8_enum_t *ep;
+
+	for (ep = enums; ep->v8e_name[0] != '\0'; ep++) {
+		if (ep->v8e_value == val)
+			return (ep->v8e_name);
+	}
+
+	return (dflt);
+}
+
+static void
+enum_print(v8_enum_t *enums)
+{
+	v8_enum_t *itp;
+
+	for (itp = enums; itp->v8e_name[0] != '\0'; itp++)
+		mdb_printf("%-30s = 0x%02x\n", itp->v8e_name, itp->v8e_value);
+}
+
+/*
+ * b[v]snprintf behave like [v]snprintf(3c), except that they update the buffer
+ * and length arguments based on how much buffer space is used by the operation.
+ * This makes it much easier to combine multiple calls in sequence without
+ * worrying about buffer overflow.
+ */
+static size_t
+bvsnprintf(char **bufp, size_t *buflenp, const char *format, va_list alist)
+{
+	size_t rv, len;
+
+	if (*buflenp == 0)
+		return (vsnprintf(NULL, 0, format, alist));
+
+	rv = vsnprintf(*bufp, *buflenp, format, alist);
+
+	len = MIN(rv, *buflenp);
+	*buflenp -= len;
+	*bufp += len;
+
+	return (len);
+}
+
+static size_t
+bsnprintf(char **bufp, size_t *buflenp, const char *format, ...)
+{
+	va_list alist;
+	size_t rv;
+
+	va_start(alist, format);
+	rv = bvsnprintf(bufp, buflenp, format, alist);
+	va_end(alist);
+
+	return (rv);
+}
+
+static void
+v8_warn(const char *format, ...)
+{
+	char buf[512];
+	va_list alist;
+	int len;
+
+	if (v8_silent)
+		return;
+
+	va_start(alist, format);
+	(void) vsnprintf(buf, sizeof (buf), format, alist);
+	va_end(alist);
+
+	/*
+	 * This is made slightly annoying because we need to effectively
+	 * preserve the original format string to allow for mdb to use the
+	 * new-line at the end to indicate that strerror should be elided.
+	 */
+	if ((len = strlen(format)) > 0 && format[len - 1] == '\n') {
+		buf[strlen(buf) - 1] = '\0';
+		mdb_warn("%s\n", buf);
+	} else {
+		mdb_warn("%s", buf);
+	}
+}
+
+/*
+ * Returns in "offp" the offset of field "field" in C++ class "klass".
+ */
+static int
+heap_offset(const char *klass, const char *field, ssize_t *offp)
+{
+	v8_class_t *clp;
+	v8_field_t *flp;
+
+	for (clp = v8_classes; clp != NULL; clp = clp->v8c_next) {
+		if (strcmp(klass, clp->v8c_name) == 0)
+			break;
+	}
+
+	if (clp == NULL)
+		return (-1);
+
+	for (flp = clp->v8c_fields; flp != NULL; flp = flp->v8f_next) {
+		if (strcmp(field, flp->v8f_name) == 0)
+			break;
+	}
+
+	if (flp == NULL)
+		return (-1);
+
+	*offp = V8_OFF_HEAP(flp->v8f_offset);
+	return (0);
+}
+
+/*
+ * Assuming "addr" is an instance of the C++ heap class "klass", read into *valp
+ * the pointer-sized value of field "field".
+ */
+static int
+read_heap_ptr(uintptr_t *valp, uintptr_t addr, ssize_t off)
+{
+	if (mdb_vread(valp, sizeof (*valp), addr + off) == -1) {
+		v8_warn("failed to read offset %d from %p", off, addr);
+		return (-1);
+	}
+
+	return (0);
+}
+
+/*
+ * Like read_heap_ptr, but assume the field is an SMI and store the actual value
+ * into *valp rather than the encoded representation.
+ */
+static int
+read_heap_smi(uintptr_t *valp, uintptr_t addr, ssize_t off)
+{
+	if (read_heap_ptr(valp, addr, off) != 0)
+		return (-1);
+
+	if (!V8_IS_SMI(*valp)) {
+		v8_warn("expected SMI, got %p\n", *valp);
+		return (-1);
+	}
+
+	*valp = V8_SMI_VALUE(*valp);
+
+	return (0);
+}
+
+static int
+read_heap_double(double *valp, uintptr_t addr, ssize_t off)
+{
+	if (mdb_vread(valp, sizeof (*valp), addr + off) == -1) {
+		v8_warn("failed to read heap value at %p", addr + off);
+		return (-1);
+	}
+
+	return (0);
+}
+
+/*
+ * Assuming "addr" refers to a FixedArray, return a newly-allocated array
+ * representing its contents.
+ */
+static int
+read_heap_array(uintptr_t addr, uintptr_t **retp, size_t *lenp, int flags)
+{
+	uint8_t type;
+	uintptr_t len;
+
+	if (!V8_IS_HEAPOBJECT(addr))
+		return (-1);
+
+	if (read_typebyte(&type, addr) != 0)
+		return (-1);
+
+	if (type != V8_TYPE_FIXEDARRAY)
+		return (-1);
+
+	if (read_heap_smi(&len, addr, V8_OFF_FIXEDARRAY_LENGTH) != 0)
+		return (-1);
+
+	*lenp = len;
+
+	if (len == 0) {
+		*retp = NULL;
+		return (0);
+	}
+
+	if ((*retp = mdb_zalloc(len * sizeof (uintptr_t), flags)) == NULL)
+		return (-1);
+
+	if (mdb_vread(*retp, len * sizeof (uintptr_t),
+	    addr + V8_OFF_FIXEDARRAY_DATA) == -1) {
+		if (!(flags & UM_GC))
+			mdb_free(*retp, len * sizeof (uintptr_t));
+
+		return (-1);
+	}
+
+	return (0);
+}
+
+static int
+read_heap_byte(uint8_t *valp, uintptr_t addr, ssize_t off)
+{
+	if (mdb_vread(valp, sizeof (*valp), addr + off) == -1) {
+		v8_warn("failed to read heap value at %p", addr + off);
+		return (-1);
+	}
+
+	return (0);
+}
+
+/*
+ * Given a heap object, returns in *valp the byte describing the type of the
+ * object.  This is shorthand for first retrieving the Map at the start of the
+ * heap object and then retrieving the type byte from the Map object.
+ */
+static int
+read_typebyte(uint8_t *valp, uintptr_t addr)
+{
+	uintptr_t mapaddr;
+	ssize_t off = V8_OFF_HEAPOBJECT_MAP;
+
+	if (mdb_vread(&mapaddr, sizeof (mapaddr), addr + off) == -1) {
+		v8_warn("failed to read type of %p", addr);
+		return (-1);
+	}
+
+	if (!V8_IS_HEAPOBJECT(mapaddr)) {
+		v8_warn("object map is not a heap object\n");
+		return (-1);
+	}
+
+	if (read_heap_byte(valp, mapaddr, V8_OFF_MAP_INSTANCE_ATTRIBUTES) == -1)
+		return (-1);
+
+	return (0);
+}
+
+/*
+ * Given a heap object, returns in *valp the size of the object.  For
+ * variable-size objects, returns an undefined value.
+ */
+static int
+read_size(size_t *valp, uintptr_t addr)
+{
+	uintptr_t mapaddr;
+	uint8_t size;
+
+	if (read_heap_ptr(&mapaddr, addr, V8_OFF_HEAPOBJECT_MAP) != 0)
+		return (-1);
+
+	if (!V8_IS_HEAPOBJECT(mapaddr)) {
+		v8_warn("heap object map is not itself a heap object\n");
+		return (-1);
+	}
+
+	if (read_heap_byte(&size, mapaddr, V8_OFF_MAP_INSTANCE_SIZE) != 0)
+		return (-1);
+
+	*valp = size << V8_PointerSizeLog2;
+	return (0);
+}
+
+/*
+ * Assuming "addr" refers to a FixedArray that is implementing a
+ * StringDictionary, iterate over its contents calling the specified function
+ * with key and value.
+ */
+static int
+read_heap_dict(uintptr_t addr,
+    int (*func)(const char *, uintptr_t, void *), void *arg)
+{
+	uint8_t type;
+	uintptr_t len;
+	char buf[512];
+	char *bufp;
+	int rval = -1;
+	uintptr_t *dict, ndict, i;
+	const char *typename;
+
+	if (read_heap_array(addr, &dict, &ndict, UM_SLEEP) != 0)
+		return (-1);
+
+	if (V8_DICT_ENTRY_SIZE < 2) {
+		v8_warn("dictionary entry size (%d) is too small for a "
+		    "key and value\n", V8_DICT_ENTRY_SIZE);
+		goto out;
+	}
+
+	for (i = V8_DICT_START_INDEX + V8_DICT_PREFIX_SIZE; i < ndict;
+	    i += V8_DICT_ENTRY_SIZE) {
+		/*
+		 * The layout here is key, value, details. (This is hardcoded
+		 * in Dictionary<Shape, Key>::SetEntry().)
+		 */
+		if (jsobj_is_undefined(dict[i]))
+			continue;
+
+		if (read_typebyte(&type, dict[i]) != 0)
+			goto out;
+
+		typename = enum_lookup_str(v8_types, type, NULL);
+
+		if (typename != NULL && strcmp(typename, "Oddball") == 0) {
+			/*
+			 * In some cases, the key can (apparently) be a hole;
+			 * assume that any Oddball in the key field falls into
+			 * this case and skip over it.
+			 */
+			continue;
+		}
+
+		if (!V8_TYPE_STRING(type))
+			goto out;
+
+		bufp = buf;
+		len = sizeof (buf);
+
+		if (jsstr_print(dict[i], JSSTR_NUDE, &bufp, &len) != 0)
+			goto out;
+
+		if (func(buf, dict[i + 1], arg) == -1)
+			goto out;
+	}
+
+	rval = 0;
+out:
+	mdb_free(dict, ndict * sizeof (uintptr_t));
+
+	return (rval);
+}
+
+/*
+ * Returns in "buf" a description of the type of "addr" suitable for printing.
+ */
+static int
+obj_jstype(uintptr_t addr, char **bufp, size_t *lenp, uint8_t *typep)
+{
+	uint8_t typebyte;
+	uintptr_t strptr;
+	const char *typename;
+
+	if (V8_IS_FAILURE(addr)) {
+		if (typep)
+			*typep = 0;
+		(void) bsnprintf(bufp, lenp, "'Failure' object");
+		return (0);
+	}
+
+	if (V8_IS_SMI(addr)) {
+		if (typep)
+			*typep = 0;
+		(void) bsnprintf(bufp, lenp, "SMI: value = %d",
+		    V8_SMI_VALUE(addr));
+		return (0);
+	}
+
+	if (read_typebyte(&typebyte, addr) != 0)
+		return (-1);
+
+	if (typep)
+		*typep = typebyte;
+
+	typename = enum_lookup_str(v8_types, typebyte, "<unknown>");
+	(void) bsnprintf(bufp, lenp, typename);
+
+	if (strcmp(typename, "Oddball") == 0) {
+		if (read_heap_ptr(&strptr, addr,
+		    V8_OFF_ODDBALL_TO_STRING) != -1) {
+			(void) bsnprintf(bufp, lenp, ": \"");
+			(void) jsstr_print(strptr, JSSTR_NUDE, bufp, lenp);
+			(void) bsnprintf(bufp, lenp, "\"");
+		}
+	}
+
+	return (0);
+}
+
+/*
+ * Print out the fields of the given object that come from the given class.
+ */
+static int
+obj_print_fields(uintptr_t baddr, v8_class_t *clp)
+{
+	v8_field_t *flp;
+	uintptr_t addr, value;
+	int rv;
+	char *bufp;
+	size_t len;
+	uint8_t type;
+	char buf[256];
+
+	for (flp = clp->v8c_fields; flp != NULL; flp = flp->v8f_next) {
+		bufp = buf;
+		len = sizeof (buf);
+
+		addr = baddr + V8_OFF_HEAP(flp->v8f_offset);
+
+		if (flp->v8f_isstr) {
+			if (mdb_readstr(buf, sizeof (buf), addr) == -1) {
+				mdb_printf("%p %s (unreadable)\n",
+				    addr, flp->v8f_name);
+				continue;
+			}
+
+			mdb_printf("%p %s = \"%s\"\n",
+			    addr, flp->v8f_name, buf);
+			continue;
+		}
+
+		if (flp->v8f_isbyte) {
+			uint8_t sv;
+			if (mdb_vread(&sv, sizeof (sv), addr) == -1) {
+				mdb_printf("%p %s (unreadable)\n",
+				    addr, flp->v8f_name);
+				continue;
+			}
+
+			mdb_printf("%p %s = 0x%x\n", addr, flp->v8f_name, sv);
+			continue;
+		}
+
+		rv = mdb_vread((void *)&value, sizeof (value), addr);
+
+		if (rv != sizeof (value) ||
+		    obj_jstype(value, &bufp, &len, &type) != 0) {
+			mdb_printf("%p %s (unreadable)\n", addr, flp->v8f_name);
+			continue;
+		}
+
+		if (type != 0 && V8_TYPE_STRING(type)) {
+			(void) bsnprintf(&bufp, &len, ": ");
+			(void) jsstr_print(value, JSSTR_QUOTED, &bufp, &len);
+		}
+
+		mdb_printf("%p %s = %p (%s)\n", addr, flp->v8f_name, value,
+		    buf);
+	}
+
+	return (DCMD_OK);
+}
+
+/*
+ * Print out all fields of the given object, starting with the root of the class
+ * hierarchy and working down the most specific type.
+ */
+static int
+obj_print_class(uintptr_t addr, v8_class_t *clp)
+{
+	int rv = 0;
+
+	/*
+	 * If we have no fields, we just print a simple inheritance hierarchy.
+	 * If we have fields but our parent doesn't, our header includes the
+	 * inheritance hierarchy.
+	 */
+	if (clp->v8c_end == 0) {
+		mdb_printf("%s ", clp->v8c_name);
+
+		if (clp->v8c_parent != NULL) {
+			mdb_printf("< ");
+			(void) obj_print_class(addr, clp->v8c_parent);
+		}
+
+		return (0);
+	}
+
+	mdb_printf("%p %s", addr, clp->v8c_name);
+
+	if (clp->v8c_start == 0 && clp->v8c_parent != NULL) {
+		mdb_printf(" < ");
+		(void) obj_print_class(addr, clp->v8c_parent);
+	}
+
+	mdb_printf(" {\n");
+	(void) mdb_inc_indent(4);
+
+	if (clp->v8c_start > 0 && clp->v8c_parent != NULL)
+		rv = obj_print_class(addr, clp->v8c_parent);
+
+	rv |= obj_print_fields(addr, clp);
+	(void) mdb_dec_indent(4);
+	mdb_printf("}\n");
+
+	return (rv);
+}
+
+/*
+ * Print the ASCII string for the given ASCII JS string, expanding ConsStrings
+ * and ExternalStrings as needed.
+ */
+static int jsstr_print_seq(uintptr_t, uint_t, char **, size_t *);
+static int jsstr_print_cons(uintptr_t, uint_t, char **, size_t *);
+static int jsstr_print_external(uintptr_t, uint_t, char **, size_t *);
+
+static int
+jsstr_print(uintptr_t addr, uint_t flags, char **bufp, size_t *lenp)
+{
+	uint8_t typebyte;
+	int err = 0;
+	char *lbufp;
+	size_t llen;
+	char buf[64];
+	boolean_t verbose = flags & JSSTR_VERBOSE ? B_TRUE : B_FALSE;
+
+	if (read_typebyte(&typebyte, addr) != 0)
+		return (0);
+
+	if (!V8_TYPE_STRING(typebyte)) {
+		(void) bsnprintf(bufp, lenp, "<not a string>");
+		return (0);
+	}
+
+	if (!V8_STRENC_ASCII(typebyte)) {
+		(void) bsnprintf(bufp, lenp, "<two-byte string>");
+		return (0);
+	}
+
+	if (verbose) {
+		lbufp = buf;
+		llen = sizeof (buf);
+		(void) obj_jstype(addr, &lbufp, &llen, NULL);
+		mdb_printf("%s\n", buf);
+		(void) mdb_inc_indent(4);
+	}
+
+	if (V8_STRREP_SEQ(typebyte))
+		err = jsstr_print_seq(addr, flags, bufp, lenp);
+	else if (V8_STRREP_CONS(typebyte))
+		err = jsstr_print_cons(addr, flags, bufp, lenp);
+	else if (V8_STRREP_EXT(typebyte))
+		err = jsstr_print_external(addr, flags, bufp, lenp);
+	else {
+		(void) bsnprintf(bufp, lenp, "<unknown string type>");
+		err = -1;
+	}
+
+	if (verbose)
+		(void) mdb_dec_indent(4);
+
+	return (err);
+}
+
+static int
+jsstr_print_seq(uintptr_t addr, uint_t flags, char **bufp, size_t *lenp)
+{
+	/*
+	 * To allow the caller to allocate a very large buffer for strings,
+	 * we'll allocate a buffer sized based on our input, making it at
+	 * least enough space for our ellipsis and at most 256K.
+	 */
+	uintptr_t len, rlen, blen = *lenp + sizeof ("[...]") + 1;
+	char *buf = alloca(MIN(blen, 256 * 1024));
+	boolean_t verbose = flags & JSSTR_VERBOSE ? B_TRUE : B_FALSE;
+	boolean_t quoted = flags & JSSTR_QUOTED ? B_TRUE : B_FALSE;
+
+	if (read_heap_smi(&len, addr, V8_OFF_STRING_LENGTH) != 0)
+		return (-1);
+
+	rlen = len <= blen - 1 ? len : blen - sizeof ("[...]");
+
+	if (verbose)
+		mdb_printf("length: %d, will read: %d\n", len, rlen);
+
+	buf[0] = '\0';
+
+	if (rlen > 0 && mdb_readstr(buf, rlen + 1,
+	    addr + V8_OFF_SEQASCIISTR_CHARS) == -1) {
+		v8_warn("failed to read SeqString data");
+		return (-1);
+	}
+
+	if (rlen != len)
+		(void) strlcat(buf, "[...]", blen);
+
+	if (verbose)
+		mdb_printf("value: \"%s\"\n", buf);
+
+	(void) bsnprintf(bufp, lenp, "%s%s%s",
+	    quoted ? "\"" : "", buf, quoted ? "\"" : "");
+
+	return (0);
+}
+
+static int
+jsstr_print_cons(uintptr_t addr, uint_t flags, char **bufp, size_t *lenp)
+{
+	boolean_t verbose = flags & JSSTR_VERBOSE ? B_TRUE : B_FALSE;
+	boolean_t quoted = flags & JSSTR_QUOTED ? B_TRUE : B_FALSE;
+	uintptr_t ptr1, ptr2;
+
+	if (read_heap_ptr(&ptr1, addr, V8_OFF_CONSSTRING_FIRST) != 0 ||
+	    read_heap_ptr(&ptr2, addr, V8_OFF_CONSSTRING_SECOND) != 0)
+		return (-1);
+
+	if (verbose) {
+		mdb_printf("ptr1: %p\n", ptr1);
+		mdb_printf("ptr2: %p\n", ptr2);
+	}
+
+	if (quoted)
+		(void) bsnprintf(bufp, lenp, "\"");
+
+	if (jsstr_print(ptr1, verbose, bufp, lenp) != 0)
+		return (-1);
+
+	if (jsstr_print(ptr2, verbose, bufp, lenp) != 0)
+		return (-1);
+
+	if (quoted)
+		(void) bsnprintf(bufp, lenp, "\"");
+
+	return (0);
+}
+
+static int
+jsstr_print_external(uintptr_t addr, uint_t flags, char **bufp,
+    size_t *lenp)
+{
+	uintptr_t ptr1, ptr2;
+	size_t blen = *lenp + 1;
+	char *buf = alloca(blen);
+	boolean_t quoted = flags & JSSTR_QUOTED ? B_TRUE : B_FALSE;
+
+	if (flags & JSSTR_VERBOSE)
+		mdb_printf("assuming Node.js string\n");
+
+	if (read_heap_ptr(&ptr1, addr, V8_OFF_EXTERNALSTRING_RESOURCE) != 0)
+		return (-1);
+
+	if (mdb_vread(&ptr2, sizeof (ptr2),
+	    ptr1 + NODE_OFF_EXTSTR_DATA) == -1) {
+		v8_warn("failed to read node external pointer: %p",
+		    ptr1 + NODE_OFF_EXTSTR_DATA);
+		return (-1);
+	}
+
+	if (mdb_readstr(buf, blen, ptr2) == -1) {
+		v8_warn("failed to read ExternalString data");
+		return (-1);
+	}
+
+	if (buf[0] != '\0' && !isascii(buf[0])) {
+		v8_warn("failed to read ExternalString ascii data\n");
+		return (-1);
+	}
+
+	(void) bsnprintf(bufp, lenp, "%s%s%s",
+	    quoted ? "\"" : "", buf, quoted ? "\"" : "");
+
+	return (0);
+}
+
+/*
+ * Returns true if the given address refers to the "undefined" object.  Returns
+ * false on failure (since we shouldn't fail on the actual "undefined" value).
+ */
+static boolean_t
+jsobj_is_undefined(uintptr_t addr)
+{
+	uint8_t type;
+	uintptr_t strptr;
+	const char *typename;
+	char buf[16];
+	char *bufp = buf;
+	size_t len = sizeof (buf);
+
+	v8_silent++;
+
+	if (read_typebyte(&type, addr) != 0) {
+		v8_silent--;
+		return (B_FALSE);
+	}
+
+	v8_silent--;
+
+	typename = enum_lookup_str(v8_types, type, "<unknown>");
+	if (strcmp(typename, "Oddball") != 0)
+		return (B_FALSE);
+
+	if (read_heap_ptr(&strptr, addr, V8_OFF_ODDBALL_TO_STRING) == -1)
+		return (B_FALSE);
+
+	if (jsstr_print(strptr, JSSTR_NUDE, &bufp, &len) != 0)
+		return (B_FALSE);
+
+	return (strcmp(buf, "undefined") == 0);
+}
+
+static int
+jsobj_properties(uintptr_t addr,
+    int (*func)(const char *, uintptr_t, void *), void *arg)
+{
+	uintptr_t ptr, map;
+	uintptr_t *props = NULL, *descs = NULL, *content = NULL, *trans;
+	size_t size, nprops, ndescs, ncontent, ntrans;
+	ssize_t ii, rndescs;
+	uint8_t type, ninprops;
+	int rval = -1;
+	size_t ps = sizeof (uintptr_t);
+	ssize_t off;
+
+	/*
+	 * Objects have either "fast" properties represented with a FixedArray
+	 * or slow properties represented with a Dictionary.
+	 */
+	if (mdb_vread(&ptr, ps, addr + V8_OFF_JSOBJECT_PROPERTIES) == -1)
+		return (-1);
+
+	if (read_typebyte(&type, ptr) != 0)
+		return (-1);
+
+	if (type != V8_TYPE_FIXEDARRAY) {
+		/*
+		 * If our properties aren't a fixed array, we'll emit a member
+		 * that contains the type name, but with a NULL value.
+		 */
+		char buf[256];
+
+		(void) mdb_snprintf(buf, sizeof (buf), "<%s>",
+		    enum_lookup_str(v8_types, type, "unknown"));
+
+		return (func(buf, NULL, arg));
+	}
+
+	/*
+	 * To iterate the properties, we need to examine the instance
+	 * descriptors of the associated Map object.  Depending on the version
+	 * of V8, this might be found directly from the map -- or indirectly
+	 * via the transitions array.
+	 */
+	if (mdb_vread(&map, ps, addr + V8_OFF_HEAPOBJECT_MAP) == -1)
+		goto err;
+
+	if (V8_DICT_SHIFT != -1) {
+		uintptr_t bit_field3;
+
+		if (mdb_vread(&bit_field3, sizeof (bit_field3),
+		    map + V8_OFF_MAP_BIT_FIELD3) == -1)
+			goto err;
+
+		if (V8_SMI_VALUE(bit_field3) & (1 << V8_DICT_SHIFT))
+			return (read_heap_dict(ptr, func, arg));
+	} else if (V8_OFF_MAP_INSTANCE_DESCRIPTORS != -1) {
+		uintptr_t bit_field3;
+
+		if (mdb_vread(&bit_field3, sizeof (bit_field3),
+		    map + V8_OFF_MAP_INSTANCE_DESCRIPTORS) == -1)
+			goto err;
+
+		if (V8_SMI_VALUE(bit_field3) == (1 << V8_ISSHARED_SHIFT)) {
+			/*
+			 * On versions of V8 prior to that used in 0.10,
+			 * the instance descriptors were overloaded to also
+			 * be bit_field3 -- and there was no way from that
+			 * field to infer a dictionary type.  Because we
+			 * can't determine if the map is actually the
+			 * hash_table_map, we assume that if it's an object
+			 * that has kIsShared set, that it is in fact a
+			 * dictionary -- an assumption that is assuredly in
+			 * error in some cases.
+			 */
+			return (read_heap_dict(ptr, func, arg));
+		}
+	}
+
+	if (read_heap_array(ptr, &props, &nprops, UM_SLEEP) != 0)
+		goto err;
+
+	if ((off = V8_OFF_MAP_INSTANCE_DESCRIPTORS) == -1) {
+		if (V8_OFF_MAP_TRANSITIONS == -1 ||
+		    V8_TRANSITIONS_IDX_DESC == -1 ||
+		    V8_PROP_IDX_CONTENT != -1) {
+			mdb_warn("missing instance_descriptors, but did "
+			    "not find expected transitions array metadata; "
+			    "cannot read properties\n");
+			goto err;
+		}
+
+		off = V8_OFF_MAP_TRANSITIONS;
+	}
+
+	if (mdb_vread(&ptr, ps, map + off) == -1)
+		goto err;
+
+	if (V8_OFF_MAP_INSTANCE_DESCRIPTORS == -1) {
+		if (read_heap_array(ptr, &trans, &ntrans, UM_SLEEP) != 0)
+			goto err;
+
+		ptr = trans[V8_TRANSITIONS_IDX_DESC];
+		mdb_free(trans, ntrans * sizeof (uintptr_t));
+	}
+
+	if (read_heap_array(ptr, &descs, &ndescs, UM_SLEEP) != 0)
+		goto err;
+
+	if (read_size(&size, addr) != 0)
+		size = 0;
+
+	if (mdb_vread(&ninprops, 1, map + V8_OFF_MAP_INOBJECT_PROPERTIES) == -1)
+		goto err;
+
+	if (V8_PROP_IDX_CONTENT != -1 && V8_PROP_IDX_CONTENT < ndescs &&
+	    read_heap_array(descs[V8_PROP_IDX_CONTENT], &content,
+	    &ncontent, UM_SLEEP) != 0)
+		goto err;
+
+	if (V8_PROP_IDX_CONTENT == -1) {
+		/*
+		 * On node v0.8 and later, the content is not stored in an
+		 * orthogonal FixedArray, but rather with the descriptors.
+		 */
+		content = descs;
+		ncontent = ndescs;
+		rndescs = ndescs > V8_PROP_IDX_FIRST ?
+		    (ndescs - V8_PROP_IDX_FIRST) / V8_PROP_DESC_SIZE : 0;
+	} else {
+		rndescs = ndescs - V8_PROP_IDX_FIRST;
+	}
+
+	for (ii = 0; ii < rndescs; ii++) {
+		uintptr_t keyidx, validx, detidx, baseidx;
+		char buf[1024];
+		intptr_t val;
+		size_t len = sizeof (buf);
+		char *c = buf;
+
+		if (V8_PROP_IDX_CONTENT != -1) {
+			/*
+			 * In node versions prior to v0.8, this was hardcoded
+			 * in the V8 implementation, so we hardcode it here
+			 * as well.
+			 */
+			keyidx = ii + V8_PROP_IDX_FIRST;
+			validx = ii << 1;
+			detidx = (ii << 1) + 1;
+		} else {
+			baseidx = V8_PROP_IDX_FIRST + (ii * V8_PROP_DESC_SIZE);
+			keyidx = baseidx + V8_PROP_DESC_KEY;
+			validx = baseidx + V8_PROP_DESC_VALUE;
+			detidx = baseidx + V8_PROP_DESC_DETAILS;
+		}
+
+		if (detidx >= ncontent) {
+			v8_warn("property descriptor %d: detidx (%d) "
+			    "out of bounds for content array (length %d)\n",
+			    ii, detidx, ncontent);
+			continue;
+		}
+
+		if (!V8_DESC_ISFIELD(content[detidx]))
+			continue;
+
+		if (keyidx >= ndescs) {
+			v8_warn("property descriptor %d: keyidx (%d) "
+			    "out of bounds for descriptor array (length %d)\n",
+			    ii, keyidx, ndescs);
+			continue;
+		}
+
+		if (jsstr_print(descs[keyidx], JSSTR_NUDE, &c, &len) != 0)
+			continue;
+
+		val = (intptr_t)content[validx];
+
+		if (!V8_IS_SMI(val)) {
+			v8_warn("object %p: property descriptor %d: value "
+			    "index value is not an SMI: %p\n", addr, ii, val);
+			continue;
+		}
+
+		val = V8_SMI_VALUE(val) - ninprops;
+
+		if (val < 0) {
+			/* property is stored directly in the object */
+			if (mdb_vread(&ptr, sizeof (ptr), addr + V8_OFF_HEAP(
+			    size + val * sizeof (uintptr_t))) == -1) {
+				v8_warn("failed to read in-object "
+				    "property at %p\n", addr + V8_OFF_HEAP(
+				    size + val * sizeof (uintptr_t)));
+				continue;
+			}
+		} else {
+			/* property should be in "props" array */
+			if (val >= nprops) {
+				v8_warn("property descriptor %d: value index "
+				    "value (%d) out of bounds (%d)\n", ii, val,
+				    nprops);
+				continue;
+			}
+
+			ptr = props[val];
+		}
+
+		if (func(buf, ptr, arg) != 0)
+			goto err;
+	}
+
+	rval = 0;
+err:
+	if (props != NULL)
+		mdb_free(props, nprops * sizeof (uintptr_t));
+
+	if (descs != NULL)
+		mdb_free(descs, ndescs * sizeof (uintptr_t));
+
+	if (content != NULL && V8_PROP_IDX_CONTENT != -1)
+		mdb_free(content, ncontent * sizeof (uintptr_t));
+
+	return (rval);
+}
+
+/*
+ * Given the line endings table in "lendsp", computes the line number for the
+ * given token position and print the result into "buf".  If "lendsp" is
+ * undefined, prints the token position instead.
+ */
+static int
+jsfunc_lineno(uintptr_t lendsp, uintptr_t tokpos, char *buf, size_t buflen)
+{
+	uintptr_t size, bufsz, lower, upper, ii = 0;
+	uintptr_t *data;
+
+	if (jsobj_is_undefined(lendsp)) {
+		/*
+		 * The token position is an SMI, but it comes in as its raw
+		 * value so we can more easily compare it to values in the line
+		 * endings table.  If we're just printing the position directly,
+		 * we must convert it here.
+		 */
+		mdb_snprintf(buf, buflen, "position %d", V8_SMI_VALUE(tokpos));
+		return (0);
+	}
+
+	if (read_heap_smi(&size, lendsp, V8_OFF_FIXEDARRAY_LENGTH) != 0)
+		return (-1);
+
+	bufsz = size * sizeof (data[0]);
+
+	if ((data = mdb_alloc(bufsz, UM_NOSLEEP)) == NULL) {
+		v8_warn("failed to alloc %d bytes for FixedArray data", bufsz);
+		return (-1);
+	}
+
+	if (mdb_vread(data, bufsz, lendsp + V8_OFF_FIXEDARRAY_DATA) != bufsz) {
+		v8_warn("failed to read FixedArray data");
+		mdb_free(data, bufsz);
+		return (-1);
+	}
+
+	lower = 0;
+	upper = size - 1;
+
+	if (tokpos > data[upper]) {
+		(void) strlcpy(buf, "position out of range", buflen);
+		mdb_free(data, bufsz);
+		return (0);
+	}
+
+	if (tokpos <= data[0]) {
+		(void) strlcpy(buf, "line 1", buflen);
+		mdb_free(data, bufsz);
+		return (0);
+	}
+
+	while (upper >= 1) {
+		ii = (lower + upper) >> 1;
+		if (tokpos > data[ii])
+			lower = ii + 1;
+		else if (tokpos <= data[ii - 1])
+			upper = ii - 1;
+		else
+			break;
+	}
+
+	(void) mdb_snprintf(buf, buflen, "line %d", ii + 1);
+	mdb_free(data, bufsz);
+	return (0);
+}
+
+/*
+ * Given a SharedFunctionInfo object, prints into bufp a name of the function
+ * suitable for printing.  This function attempts to infer a name for anonymous
+ * functions.
+ */
+static int
+jsfunc_name(uintptr_t funcinfop, char **bufp, size_t *lenp)
+{
+	uintptr_t ptrp;
+	char *bufs = *bufp;
+
+	if (read_heap_ptr(&ptrp, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_NAME) != 0 ||
+	    jsstr_print(ptrp, JSSTR_NUDE, bufp, lenp) != 0)
+		return (-1);
+
+	if (*bufp != bufs)
+		return (0);
+
+	if (read_heap_ptr(&ptrp, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_INFERRED_NAME) != 0) {
+		(void) bsnprintf(bufp, lenp, "<anonymous>");
+		return (0);
+	}
+
+	(void) bsnprintf(bufp, lenp, "<anonymous> (as ");
+	bufs = *bufp;
+
+	if (jsstr_print(ptrp, JSSTR_NUDE, bufp, lenp) != 0)
+		return (-1);
+
+	if (*bufp == bufs)
+		(void) bsnprintf(bufp, lenp, "<anon>");
+
+	(void) bsnprintf(bufp, lenp, ")");
+
+	return (0);
+}
+
+/*
+ * JavaScript-level object printing
+ */
+typedef struct jsobj_print {
+	char **jsop_bufp;
+	size_t *jsop_lenp;
+	int jsop_indent;
+	uint64_t jsop_depth;
+	boolean_t jsop_printaddr;
+	uintptr_t jsop_baseaddr;
+	int jsop_nprops;
+	const char *jsop_member;
+	boolean_t jsop_found;
+} jsobj_print_t;
+
+static int jsobj_print_number(uintptr_t, jsobj_print_t *);
+static int jsobj_print_oddball(uintptr_t, jsobj_print_t *);
+static int jsobj_print_jsobject(uintptr_t, jsobj_print_t *);
+static int jsobj_print_jsarray(uintptr_t, jsobj_print_t *);
+static int jsobj_print_jsfunction(uintptr_t, jsobj_print_t *);
+static int jsobj_print_jsdate(uintptr_t, jsobj_print_t *);
+
+static int
+jsobj_print(uintptr_t addr, jsobj_print_t *jsop)
+{
+	uint8_t type;
+	const char *klass;
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+
+	const struct {
+		char *name;
+		int (*func)(uintptr_t, jsobj_print_t *);
+	} table[] = {
+		{ "HeapNumber", jsobj_print_number },
+		{ "Oddball", jsobj_print_oddball },
+		{ "JSObject", jsobj_print_jsobject },
+		{ "JSArray", jsobj_print_jsarray },
+		{ "JSFunction", jsobj_print_jsfunction },
+		{ "JSDate", jsobj_print_jsdate },
+		{ NULL }
+	}, *ent;
+
+	if (jsop->jsop_baseaddr != NULL && jsop->jsop_member == NULL)
+		(void) bsnprintf(bufp, lenp, "%p: ", jsop->jsop_baseaddr);
+
+	if (jsop->jsop_printaddr && jsop->jsop_member == NULL)
+		(void) bsnprintf(bufp, lenp, "%p: ", addr);
+
+	if (V8_IS_SMI(addr)) {
+		(void) bsnprintf(bufp, lenp, "%d", V8_SMI_VALUE(addr));
+		return (0);
+	}
+
+	if (!V8_IS_HEAPOBJECT(addr)) {
+		v8_warn("not a heap object: %p\n", addr);
+		return (-1);
+	}
+
+	if (read_typebyte(&type, addr) != 0)
+		return (-1);
+
+	if (V8_TYPE_STRING(type)) {
+		if (jsstr_print(addr, JSSTR_QUOTED, bufp, lenp) == -1)
+			return (-1);
+
+		return (0);
+	}
+
+	klass = enum_lookup_str(v8_types, type, "<unknown>");
+
+	for (ent = &table[0]; ent->name != NULL; ent++) {
+		if (strcmp(klass, ent->name) == 0)
+			return (ent->func(addr, jsop));
+	}
+
+	v8_warn("%p: unknown JavaScript object type \"%s\"\n", addr, klass);
+	return (-1);
+}
+
+static int
+jsobj_print_number(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+	double numval;
+
+	if (read_heap_double(&numval, addr, V8_OFF_HEAPNUMBER_VALUE) == -1)
+		return (-1);
+
+	if (numval == (long long)numval)
+		(void) bsnprintf(bufp, lenp, "%lld", (long long)numval);
+	else
+		(void) bsnprintf(bufp, lenp, "%e", numval);
+
+	return (0);
+}
+
+static int
+jsobj_print_oddball(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+	uintptr_t strptr;
+
+	if (read_heap_ptr(&strptr, addr, V8_OFF_ODDBALL_TO_STRING) != 0)
+		return (-1);
+
+	return (jsstr_print(strptr, JSSTR_NUDE, bufp, lenp));
+}
+
+static int
+jsobj_print_prop(const char *desc, uintptr_t val, void *arg)
+{
+	jsobj_print_t *jsop = arg, descend;
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+
+	(void) bsnprintf(bufp, lenp, "%s\n%*s%s: ", jsop->jsop_nprops == 0 ?
+	    "{" : "", jsop->jsop_indent + 4, "", desc);
+
+	descend = *jsop;
+	descend.jsop_depth--;
+	descend.jsop_indent += 4;
+
+	(void) jsobj_print(val, &descend);
+	(void) bsnprintf(bufp, lenp, ",");
+
+	jsop->jsop_nprops++;
+
+	return (0);
+}
+
+static int
+jsobj_print_prop_member(const char *desc, uintptr_t val, void *arg)
+{
+	jsobj_print_t *jsop = arg, descend;
+	const char *member = jsop->jsop_member, *next = member;
+	int rv;
+
+	for (; *next != '\0' && *next != '.' && *next != '['; next++)
+		continue;
+
+	if (*member == '[') {
+		mdb_warn("cannot use array indexing on an object\n");
+		return (-1);
+	}
+
+	if (strncmp(member, desc, next - member) != 0)
+		return (0);
+
+	if (desc[next - member] != '\0')
+		return (0);
+
+	/*
+	 * This property matches the desired member; descend.
+	 */
+	descend = *jsop;
+
+	if (*next == '\0') {
+		descend.jsop_member = NULL;
+		descend.jsop_found = B_TRUE;
+	} else {
+		descend.jsop_member = *next == '.' ? next + 1 : next;
+	}
+
+	rv = jsobj_print(val, &descend);
+	jsop->jsop_found = descend.jsop_found;
+
+	return (rv);
+}
+
+static int
+jsobj_print_jsobject(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+
+	if (jsop->jsop_member != NULL)
+		return (jsobj_properties(addr, jsobj_print_prop_member, jsop));
+
+	if (jsop->jsop_depth == 0) {
+		(void) bsnprintf(bufp, lenp, "[...]");
+		return (0);
+	}
+
+	jsop->jsop_nprops = 0;
+
+	if (jsobj_properties(addr, jsobj_print_prop, jsop) != 0)
+		return (-1);
+
+	if (jsop->jsop_nprops > 0) {
+		(void) bsnprintf(bufp, lenp, "\n%*s", jsop->jsop_indent, "");
+	} else if (jsop->jsop_nprops == 0) {
+		(void) bsnprintf(bufp, lenp, "{");
+	} else {
+		(void) bsnprintf(bufp, lenp, "{ /* unknown property */ ");
+	}
+
+	(void) bsnprintf(bufp, lenp, "}");
+
+	return (0);
+}
+
+static int
+jsobj_print_jsarray_member(uintptr_t addr, jsobj_print_t *jsop)
+{
+	uintptr_t *elts;
+	jsobj_print_t descend;
+	uintptr_t ptr;
+	const char *member = jsop->jsop_member, *end, *p;
+	size_t elt = 0, place = 1, len, rv;
+
+	if (read_heap_ptr(&ptr, addr, V8_OFF_JSOBJECT_ELEMENTS) != 0 ||
+	    read_heap_array(ptr, &elts, &len, UM_SLEEP | UM_GC) != 0)
+		return (-1);
+
+	if (*member != '[') {
+		mdb_warn("expected bracketed array index; "
+		    "found '%s'\n", member);
+		return (-1);
+	}
+
+	if ((end = strchr(member, ']')) == NULL) {
+		mdb_warn("missing array index terminator\n");
+		return (-1);
+	}
+
+	/*
+	 * We know where our array index ends; convert it to an integer
+	 * by stepping through it from least significant digit to most.
+	 */
+	for (p = end - 1; p > member; p--) {
+		if (*p < '0' || *p > '9') {
+			mdb_warn("illegal array index at '%c'\n", *p);
+			return (-1);
+		}
+
+		elt += (*p - '0') * place;
+		place *= 10;
+	}
+
+	if (place == 1) {
+		mdb_warn("missing array index\n");
+		return (-1);
+	}
+
+	if (elt >= len) {
+		mdb_warn("array index %d exceeds size of %d\n", elt, len);
+		return (-1);
+	}
+
+	descend = *jsop;
+
+	switch (*(++end)) {
+	case '\0':
+		descend.jsop_member = NULL;
+		descend.jsop_found = B_TRUE;
+		break;
+
+	case '.':
+		descend.jsop_member = end + 1;
+		break;
+
+	case '[':
+		descend.jsop_member = end;
+		break;
+
+	default:
+		mdb_warn("illegal character '%c' following "
+		    "array index terminator\n", *end);
+		return (-1);
+	}
+
+	rv = jsobj_print(elts[elt], &descend);
+	jsop->jsop_found = descend.jsop_found;
+
+	return (rv);
+}
+
+static int
+jsobj_print_jsarray(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+	int indent = jsop->jsop_indent;
+	jsobj_print_t descend;
+	uintptr_t ptr;
+	uintptr_t *elts;
+	size_t ii, len;
+
+	if (jsop->jsop_member != NULL)
+		return (jsobj_print_jsarray_member(addr, jsop));
+
+	if (jsop->jsop_depth == 0) {
+		(void) bsnprintf(bufp, lenp, "[...]");
+		return (0);
+	}
+
+	if (read_heap_ptr(&ptr, addr, V8_OFF_JSOBJECT_ELEMENTS) != 0 ||
+	    read_heap_array(ptr, &elts, &len, UM_SLEEP | UM_GC) != 0)
+		return (-1);
+
+	if (len == 0) {
+		(void) bsnprintf(bufp, lenp, "[]");
+		return (0);
+	}
+
+	descend = *jsop;
+	descend.jsop_depth--;
+	descend.jsop_indent += 4;
+
+	if (len == 1) {
+		(void) bsnprintf(bufp, lenp, "[ ");
+		(void) jsobj_print(elts[0], &descend);
+		(void) bsnprintf(bufp, lenp, " ]");
+		return (0);
+	}
+
+	(void) bsnprintf(bufp, lenp, "[\n");
+
+	for (ii = 0; ii < len; ii++) {
+		(void) bsnprintf(bufp, lenp, "%*s", indent + 4, "");
+		(void) jsobj_print(elts[ii], &descend);
+		(void) bsnprintf(bufp, lenp, ",\n");
+	}
+
+	(void) bsnprintf(bufp, lenp, "%*s", indent, "");
+	(void) bsnprintf(bufp, lenp, "]");
+
+	return (0);
+}
+
+static int
+jsobj_print_jsfunction(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+	uintptr_t shared;
+
+	if (read_heap_ptr(&shared, addr, V8_OFF_JSFUNCTION_SHARED) != 0)
+		return (-1);
+
+	(void) bsnprintf(bufp, lenp, "function ");
+	return (jsfunc_name(shared, bufp, lenp) != 0);
+}
+
+static int
+jsobj_print_jsdate(uintptr_t addr, jsobj_print_t *jsop)
+{
+	char **bufp = jsop->jsop_bufp;
+	size_t *lenp = jsop->jsop_lenp;
+	char buf[128];
+	uintptr_t value;
+	uint8_t type;
+	double numval;
+
+	if (V8_OFF_JSDATE_VALUE == -1) {
+		(void) bsnprintf(bufp, lenp, "<JSDate>", buf);
+		return (0);
+	}
+
+	if (read_heap_ptr(&value, addr, V8_OFF_JSDATE_VALUE) != 0)
+		return (-1);
+
+	if (read_typebyte(&type, value) != 0)
+		return (-1);
+
+	if (strcmp(enum_lookup_str(v8_types, type, ""), "HeapNumber") != 0)
+		return (-1);
+
+	if (read_heap_double(&numval, value, V8_OFF_HEAPNUMBER_VALUE) == -1)
+		return (-1);
+
+	mdb_snprintf(buf, sizeof (buf), "%Y",
+	    (time_t)((long long)numval / MILLISEC));
+	(void) bsnprintf(bufp, lenp, "%lld (%s)", (long long)numval, buf);
+
+	return (0);
+}
+
+/*
+ * dcmd implementations
+ */
+
+/* ARGSUSED */
+static int
+dcmd_v8classes(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	v8_class_t *clp;
+
+	for (clp = v8_classes; clp != NULL; clp = clp->v8c_next)
+		mdb_printf("%s\n", clp->v8c_name);
+
+	return (DCMD_OK);
+}
+
+static int
+do_v8code(uintptr_t addr, boolean_t opt_d)
+{
+	uintptr_t instrlen;
+	ssize_t instroff = V8_OFF_CODE_INSTRUCTION_START;
+
+	if (read_heap_ptr(&instrlen, addr, V8_OFF_CODE_INSTRUCTION_SIZE) != 0)
+		return (DCMD_ERR);
+
+	mdb_printf("code: %p\n", addr);
+	mdb_printf("instructions: [%p, %p)\n", addr + instroff,
+	    addr + instroff + instrlen);
+
+	if (!opt_d)
+		return (DCMD_OK);
+
+	mdb_set_dot(addr + instroff);
+
+	do {
+		(void) mdb_inc_indent(8); /* gets reset by mdb_eval() */
+
+		/*
+		 * This is absolutely awful. We want to disassemble the above
+		 * range of instructions.  Because we don't know how many there
+		 * are, we can't use "::dis".  We resort to evaluating "./i",
+		 * but then we need to advance "." by the size of the
+		 * instruction just printed.  The only way to do that is by
+		 * printing out "+", but we don't want that to show up, so we
+		 * redirect it to /dev/null.
+		 */
+		if (mdb_eval("/i") != 0 ||
+		    mdb_eval("+=p ! cat > /dev/null") != 0) {
+			(void) mdb_dec_indent(8);
+			v8_warn("failed to disassemble at %p", mdb_get_dot());
+			return (DCMD_ERR);
+		}
+	} while (mdb_get_dot() < addr + instroff + instrlen);
+
+	(void) mdb_dec_indent(8);
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8code(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	boolean_t opt_d = B_FALSE;
+
+	if (mdb_getopts(argc, argv, 'd', MDB_OPT_SETBITS, B_TRUE, &opt_d,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	return (do_v8code(addr, opt_d));
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8function(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	uint8_t type;
+	uintptr_t funcinfop, scriptp, lendsp, tokpos, namep, codep;
+	char *bufp;
+	size_t len;
+	boolean_t opt_d = B_FALSE;
+	char buf[512];
+
+	if (mdb_getopts(argc, argv, 'd', MDB_OPT_SETBITS, B_TRUE, &opt_d,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	if (read_typebyte(&type, addr) != 0)
+		return (DCMD_ERR);
+
+	if (strcmp(enum_lookup_str(v8_types, type, ""), "JSFunction") != 0) {
+		v8_warn("%p is not an instance of JSFunction\n", addr);
+		return (DCMD_ERR);
+	}
+
+	if (read_heap_ptr(&funcinfop, addr, V8_OFF_JSFUNCTION_SHARED) != 0 ||
+	    read_heap_ptr(&tokpos, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_FUNCTION_TOKEN_POSITION) != 0 ||
+	    read_heap_ptr(&scriptp, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_SCRIPT) != 0 ||
+	    read_heap_ptr(&namep, scriptp, V8_OFF_SCRIPT_NAME) != 0 ||
+	    read_heap_ptr(&lendsp, scriptp, V8_OFF_SCRIPT_LINE_ENDS) != 0)
+		return (DCMD_ERR);
+
+	bufp = buf;
+	len = sizeof (buf);
+	if (jsfunc_name(funcinfop, &bufp, &len) != 0)
+		return (DCMD_ERR);
+
+	mdb_printf("%p: JSFunction: %s\n", addr, buf);
+
+	bufp = buf;
+	len = sizeof (buf);
+	mdb_printf("defined at ");
+
+	if (jsstr_print(namep, JSSTR_NUDE, &bufp, &len) == 0)
+		mdb_printf("%s ", buf);
+
+	if (jsfunc_lineno(lendsp, tokpos, buf, sizeof (buf)) == 0)
+		mdb_printf("%s", buf);
+
+	mdb_printf("\n");
+
+	if (read_heap_ptr(&codep,
+	    funcinfop, V8_OFF_SHAREDFUNCTIONINFO_CODE) != 0)
+		return (DCMD_ERR);
+
+	return (do_v8code(codep, opt_d));
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8frametypes(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	enum_print(v8_frametypes);
+	return (DCMD_OK);
+}
+
+static void
+dcmd_v8print_help(void)
+{
+	mdb_printf(
+	    "Prints out \".\" (a V8 heap object) as an instance of its C++\n"
+	    "class.  With no arguments, the appropriate class is detected\n"
+	    "automatically.  The 'class' argument overrides this to print an\n"
+	    "object as an instance of the given class.  The list of known\n"
+	    "classes can be viewed with ::jsclasses.");
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8print(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	const char *rqclass;
+	v8_class_t *clp;
+	char *bufp;
+	size_t len;
+	uint8_t type;
+	char buf[256];
+
+	if (argc < 1) {
+		/*
+		 * If no type was specified, determine it automatically.
+		 */
+		bufp = buf;
+		len = sizeof (buf);
+		if (obj_jstype(addr, &bufp, &len, &type) != 0)
+			return (DCMD_ERR);
+
+		if (type == 0) {
+			/* For SMI or Failure, just print out the type. */
+			mdb_printf("%s\n", buf);
+			return (DCMD_OK);
+		}
+
+		if ((rqclass = enum_lookup_str(v8_types, type, NULL)) == NULL) {
+			v8_warn("object has unknown type\n");
+			return (DCMD_ERR);
+		}
+	} else {
+		if (argv[0].a_type != MDB_TYPE_STRING)
+			return (DCMD_USAGE);
+
+		rqclass = argv[0].a_un.a_str;
+	}
+
+	for (clp = v8_classes; clp != NULL; clp = clp->v8c_next) {
+		if (strcmp(rqclass, clp->v8c_name) == 0)
+			break;
+	}
+
+	if (clp == NULL) {
+		v8_warn("unknown class '%s'\n", rqclass);
+		return (DCMD_USAGE);
+	}
+
+	return (obj_print_class(addr, clp));
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8type(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	char buf[64];
+	char *bufp = buf;
+	size_t len = sizeof (buf);
+
+	if (obj_jstype(addr, &bufp, &len, NULL) != 0)
+		return (DCMD_ERR);
+
+	mdb_printf("0x%p: %s\n", addr, buf);
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8types(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	enum_print(v8_types);
+	return (DCMD_OK);
+}
+
+static int
+load_current_context(uintptr_t *fpp, uintptr_t *raddrp)
+{
+	mdb_reg_t regfp, regip;
+
+#ifdef __amd64
+	if (mdb_getareg(1, "rbp", &regfp) != 0 ||
+	    mdb_getareg(1, "rip", &regip) != 0) {
+#else
+#ifdef __i386
+	if (mdb_getareg(1, "ebp", &regfp) != 0 ||
+	    mdb_getareg(1, "eip", &regip) != 0) {
+#else
+#error Unrecognized microprocessor
+#endif
+#endif
+		v8_warn("failed to load current context");
+		return (-1);
+	}
+
+	if (fpp != NULL)
+		*fpp = (uintptr_t)regfp;
+
+	if (raddrp != NULL)
+		*raddrp = (uintptr_t)regip;
+
+	return (0);
+}
+
+static int
+do_jsframe_special(uintptr_t fptr, uintptr_t raddr, char *prop)
+{
+	uintptr_t ftype;
+	const char *ftypename;
+
+	/*
+	 * First see if this looks like a native frame rather than a JavaScript
+	 * frame.  We check this by asking MDB to print the return address
+	 * symbolically.  If that works, we assume this was NOT a V8 frame,
+	 * since those are never in the symbol table.
+	 */
+	if (mdb_snprintf(NULL, 0, "%A", raddr) > 1) {
+		if (prop != NULL)
+			return (0);
+
+		mdb_printf("%p %a\n", fptr, raddr);
+		return (0);
+	}
+
+	/*
+	 * Figure out what kind of frame this is using the same algorithm as
+	 * V8's ComputeType function.  First, look for an ArgumentsAdaptorFrame.
+	 */
+	if (mdb_vread(&ftype, sizeof (ftype), fptr + V8_OFF_FP_CONTEXT) != -1 &&
+	    V8_IS_SMI(ftype) &&
+	    (ftypename = enum_lookup_str(v8_frametypes, V8_SMI_VALUE(ftype),
+	    NULL)) != NULL && strstr(ftypename, "ArgumentsAdaptor") != NULL) {
+		if (prop != NULL)
+			return (0);
+
+		mdb_printf("%p %a <%s>\n", fptr, raddr, ftypename);
+		return (0);
+	}
+
+	/*
+	 * Other special frame types are indicated by a marker.
+	 */
+	if (mdb_vread(&ftype, sizeof (ftype), fptr + V8_OFF_FP_MARKER) != -1 &&
+	    V8_IS_SMI(ftype)) {
+		if (prop != NULL)
+			return (0);
+
+		ftypename = enum_lookup_str(v8_frametypes, V8_SMI_VALUE(ftype),
+		    NULL);
+
+		if (ftypename != NULL)
+			mdb_printf("%p %a <%s>\n", fptr, raddr, ftypename);
+		else
+			mdb_printf("%p %a\n", fptr, raddr);
+
+		return (0);
+	}
+
+	return (-1);
+}
+
+static int
+do_jsframe(uintptr_t fptr, uintptr_t raddr, boolean_t verbose,
+    char *func, char *prop)
+{
+	uintptr_t funcp, funcinfop, tokpos, scriptp, lendsp, ptrp;
+	uintptr_t ii, nargs;
+	const char *typename;
+	char *bufp;
+	size_t len;
+	uint8_t type;
+	char buf[256];
+
+	/*
+	 * Check for non-JavaScript frames first.
+	 */
+	if (func == NULL && do_jsframe_special(fptr, raddr, prop) == 0)
+		return (DCMD_OK);
+
+	/*
+	 * At this point we assume we're looking at a JavaScript frame.  As with
+	 * native frames, fish the address out of the parent frame.
+	 */
+	if (mdb_vread(&funcp, sizeof (funcp),
+	    fptr + V8_OFF_FP_FUNCTION) == -1) {
+		v8_warn("failed to read stack at %p",
+		    fptr + V8_OFF_FP_FUNCTION);
+		return (DCMD_ERR);
+	}
+
+	/*
+	 * Check if this thing is really a JSFunction at all. For some frames,
+	 * it's a Code object, presumably indicating some internal frame.
+	 */
+	v8_silent++;
+
+	if (read_typebyte(&type, funcp) != 0 ||
+	    (typename = enum_lookup_str(v8_types, type, NULL)) == NULL) {
+		v8_silent--;
+
+		if (func != NULL || prop != NULL)
+			return (DCMD_OK);
+
+		mdb_printf("%p %a\n", fptr, raddr);
+		return (DCMD_OK);
+	}
+
+	v8_silent--;
+
+	if (strcmp("Code", typename) == 0) {
+		if (func != NULL || prop != NULL)
+			return (DCMD_OK);
+
+		mdb_printf("%p %a internal (Code: %p)\n", fptr, raddr, funcp);
+		return (DCMD_OK);
+	}
+
+	if (strcmp("JSFunction", typename) != 0) {
+		if (func != NULL || prop != NULL)
+			return (DCMD_OK);
+
+		mdb_printf("%p %a unknown (%s: %p)", fptr, raddr, typename,
+		    funcp);
+		return (DCMD_OK);
+	}
+
+	if (read_heap_ptr(&funcinfop, funcp, V8_OFF_JSFUNCTION_SHARED) != 0)
+		return (DCMD_ERR);
+
+	bufp = buf;
+	len = sizeof (buf);
+	if (jsfunc_name(funcinfop, &bufp, &len) != 0)
+		return (DCMD_ERR);
+
+	if (func != NULL && strcmp(buf, func) != 0)
+		return (DCMD_OK);
+
+	if (prop == NULL)
+		mdb_printf("%p %a %s (%p)\n", fptr, raddr, buf, funcp);
+
+	if (!verbose && prop == NULL)
+		return (DCMD_OK);
+
+	/*
+	 * Although the token position is technically an SMI, we're going to
+	 * byte-compare it to other SMI values so we don't want decode it here.
+	 */
+	if (read_heap_ptr(&tokpos, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_FUNCTION_TOKEN_POSITION) != 0)
+		return (DCMD_ERR);
+
+	if (read_heap_ptr(&scriptp, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_SCRIPT) != 0)
+		return (DCMD_ERR);
+
+	if (read_heap_ptr(&ptrp, scriptp, V8_OFF_SCRIPT_NAME) != 0)
+		return (DCMD_ERR);
+
+	bufp = buf;
+	len = sizeof (buf);
+	(void) jsstr_print(ptrp, JSSTR_NUDE, &bufp, &len);
+
+	if (prop != NULL && strcmp(prop, "file") == 0) {
+		mdb_printf("%s\n", buf);
+		return (DCMD_OK);
+	}
+
+	if (prop == NULL) {
+		(void) mdb_inc_indent(4);
+		mdb_printf("file: %s\n", buf);
+	}
+
+	if (read_heap_ptr(&lendsp, scriptp, V8_OFF_SCRIPT_LINE_ENDS) != 0)
+		return (DCMD_ERR);
+
+	(void) jsfunc_lineno(lendsp, tokpos, buf, sizeof (buf));
+
+	if (prop != NULL && strcmp(prop, "posn") == 0) {
+		mdb_printf("%s\n", buf);
+		return (DCMD_OK);
+	}
+
+	if (prop == NULL)
+		mdb_printf("posn: %s\n", buf);
+
+	if (read_heap_smi(&nargs, funcinfop,
+	    V8_OFF_SHAREDFUNCTIONINFO_LENGTH) == 0) {
+		for (ii = 0; ii < nargs; ii++) {
+			uintptr_t argptr;
+			char arg[10];
+
+			if (mdb_vread(&argptr, sizeof (argptr),
+			    fptr + V8_OFF_FP_ARGS + (nargs - ii - 1) *
+			    sizeof (uintptr_t)) == -1)
+				continue;
+
+			(void) snprintf(arg, sizeof (arg), "arg%d", ii + 1);
+
+			if (prop != NULL) {
+				if (strcmp(arg, prop) != 0)
+					continue;
+
+				mdb_printf("%p\n", argptr);
+				return (DCMD_OK);
+			}
+
+			bufp = buf;
+			len = sizeof (buf);
+			(void) obj_jstype(argptr, &bufp, &len, NULL);
+
+			mdb_printf("arg%d: %p (%s)\n", (ii + 1), argptr, buf);
+		}
+	}
+
+	if (prop != NULL) {
+		mdb_warn("unknown frame property '%s'\n", prop);
+		return (DCMD_ERR);
+	}
+
+	(void) mdb_dec_indent(4);
+
+	return (DCMD_OK);
+}
+
+typedef struct findjsobjects_prop {
+	struct findjsobjects_prop *fjsp_next;
+	char fjsp_desc[1];
+} findjsobjects_prop_t;
+
+typedef struct findjsobjects_instance {
+	uintptr_t fjsi_addr;
+	struct findjsobjects_instance *fjsi_next;
+} findjsobjects_instance_t;
+
+typedef struct findjsobjects_obj {
+	findjsobjects_prop_t *fjso_props;
+	findjsobjects_prop_t *fjso_last;
+	size_t fjso_nprops;
+	findjsobjects_instance_t fjso_instances;
+	int fjso_ninstances;
+	avl_node_t fjso_node;
+	struct findjsobjects_obj *fjso_next;
+	boolean_t fjso_malformed;
+	char fjso_constructor[80];
+} findjsobjects_obj_t;
+
+typedef struct findjsobjects_stats {
+	int fjss_heapobjs;
+	int fjss_cached;
+	int fjss_typereads;
+	int fjss_jsobjs;
+	int fjss_objects;
+	int fjss_arrays;
+	int fjss_uniques;
+} findjsobjects_stats_t;
+
+typedef struct findjsobjects_reference {
+	uintptr_t fjsrf_addr;
+	char *fjsrf_desc;
+	size_t fjsrf_index;
+	struct findjsobjects_reference *fjsrf_next;
+} findjsobjects_reference_t;
+
+typedef struct findjsobjects_referent {
+	avl_node_t fjsr_node;
+	uintptr_t fjsr_addr;
+	findjsobjects_reference_t *fjsr_head;
+	findjsobjects_reference_t *fjsr_tail;
+	struct findjsobjects_referent *fjsr_next;
+} findjsobjects_referent_t;
+
+typedef struct findjsobjects_state {
+	uintptr_t fjs_addr;
+	uintptr_t fjs_size;
+	boolean_t fjs_verbose;
+	boolean_t fjs_brk;
+	boolean_t fjs_allobjs;
+	boolean_t fjs_initialized;
+	boolean_t fjs_marking;
+	boolean_t fjs_referred;
+	avl_tree_t fjs_tree;
+	avl_tree_t fjs_referents;
+	findjsobjects_referent_t *fjs_head;
+	findjsobjects_referent_t *fjs_tail;
+	findjsobjects_obj_t *fjs_current;
+	findjsobjects_obj_t *fjs_objects;
+	findjsobjects_stats_t fjs_stats;
+} findjsobjects_state_t;
+
+findjsobjects_obj_t *
+findjsobjects_alloc(uintptr_t addr)
+{
+	findjsobjects_obj_t *obj;
+
+	obj = mdb_zalloc(sizeof (findjsobjects_obj_t), UM_SLEEP);
+	obj->fjso_instances.fjsi_addr = addr;
+	obj->fjso_ninstances = 1;
+
+	return (obj);
+}
+
+void
+findjsobjects_free(findjsobjects_obj_t *obj)
+{
+	findjsobjects_prop_t *prop, *next;
+
+	for (prop = obj->fjso_props; prop != NULL; prop = next) {
+		next = prop->fjsp_next;
+		mdb_free(prop, sizeof (findjsobjects_prop_t) +
+		    strlen(prop->fjsp_desc));
+	}
+
+	mdb_free(obj, sizeof (findjsobjects_obj_t));
+}
+
+int
+findjsobjects_cmp(findjsobjects_obj_t *lhs, findjsobjects_obj_t *rhs)
+{
+	findjsobjects_prop_t *lprop, *rprop;
+	int rv;
+
+	lprop = lhs->fjso_props;
+	rprop = rhs->fjso_props;
+
+	while (lprop != NULL && rprop != NULL) {
+		if ((rv = strcmp(lprop->fjsp_desc, rprop->fjsp_desc)) != 0)
+			return (rv > 0 ? 1 : -1);
+
+		lprop = lprop->fjsp_next;
+		rprop = rprop->fjsp_next;
+	}
+
+	if (lprop != NULL)
+		return (1);
+
+	if (rprop != NULL)
+		return (-1);
+
+	if (lhs->fjso_nprops > rhs->fjso_nprops)
+		return (1);
+
+	if (lhs->fjso_nprops < rhs->fjso_nprops)
+		return (-1);
+
+	rv = strcmp(lhs->fjso_constructor, rhs->fjso_constructor);
+
+	return (rv < 0 ? -1 : rv > 0 ? 1 : 0);
+}
+
+int
+findjsobjects_cmp_referents(findjsobjects_referent_t *lhs,
+    findjsobjects_referent_t *rhs)
+{
+	if (lhs->fjsr_addr < rhs->fjsr_addr)
+		return (-1);
+
+	if (lhs->fjsr_addr > rhs->fjsr_addr)
+		return (1);
+
+	return (0);
+}
+
+int
+findjsobjects_cmp_ninstances(const void *l, const void *r)
+{
+	findjsobjects_obj_t *lhs = *((findjsobjects_obj_t **)l);
+	findjsobjects_obj_t *rhs = *((findjsobjects_obj_t **)r);
+	size_t lprod = lhs->fjso_ninstances * lhs->fjso_nprops;
+	size_t rprod = rhs->fjso_ninstances * rhs->fjso_nprops;
+
+	if (lprod < rprod)
+		return (-1);
+
+	if (lprod > rprod)
+		return (1);
+
+	if (lhs->fjso_ninstances < rhs->fjso_ninstances)
+		return (-1);
+
+	if (lhs->fjso_ninstances > rhs->fjso_ninstances)
+		return (1);
+
+	if (lhs->fjso_nprops < rhs->fjso_nprops)
+		return (-1);
+
+	if (lhs->fjso_nprops > rhs->fjso_nprops)
+		return (1);
+
+	return (0);
+}
+
+/*ARGSUSED*/
+int
+findjsobjects_prop(const char *desc, uintptr_t val, void *arg)
+{
+	findjsobjects_state_t *fjs = arg;
+	findjsobjects_obj_t *current = fjs->fjs_current;
+	findjsobjects_prop_t *prop;
+
+	if (desc == NULL)
+		desc = "<unknown>";
+
+	prop = mdb_zalloc(sizeof (findjsobjects_prop_t) +
+	    strlen(desc), UM_SLEEP);
+
+	strcpy(prop->fjsp_desc, desc);
+
+	if (current->fjso_last != NULL) {
+		current->fjso_last->fjsp_next = prop;
+	} else {
+		current->fjso_props = prop;
+	}
+
+	current->fjso_last = prop;
+	current->fjso_nprops++;
+	current->fjso_malformed =
+	    val == NULL && current->fjso_nprops == 1 && desc[0] == '<';
+
+	return (0);
+}
+
+static void
+findjsobjects_constructor(findjsobjects_obj_t *obj)
+{
+	char *bufp = obj->fjso_constructor;
+	size_t len = sizeof (obj->fjso_constructor);
+	uintptr_t map, funcinfop;
+	uintptr_t addr = obj->fjso_instances.fjsi_addr;
+	uint8_t type;
+
+	v8_silent++;
+
+	if (read_heap_ptr(&map, addr, V8_OFF_HEAPOBJECT_MAP) != 0 ||
+	    read_heap_ptr(&addr, map, V8_OFF_MAP_CONSTRUCTOR) != 0)
+		goto out;
+
+	if (read_typebyte(&type, addr) != 0)
+		goto out;
+
+	if (strcmp(enum_lookup_str(v8_types, type, ""), "JSFunction") != 0)
+		goto out;
+
+	if (read_heap_ptr(&funcinfop, addr, V8_OFF_JSFUNCTION_SHARED) != 0)
+		goto out;
+
+	if (jsfunc_name(funcinfop, &bufp, &len) != 0)
+		goto out;
+out:
+	v8_silent--;
+}
+
+int
+findjsobjects_range(findjsobjects_state_t *fjs, uintptr_t addr, uintptr_t size)
+{
+	uintptr_t limit;
+	findjsobjects_stats_t *stats = &fjs->fjs_stats;
+	uint8_t type;
+	int jsobject = V8_TYPE_JSOBJECT, jsarray = V8_TYPE_JSARRAY;
+	caddr_t range = mdb_alloc(size, UM_SLEEP);
+	uintptr_t base = addr, mapaddr;
+
+	if (mdb_vread(range, size, addr) == -1)
+		return (0);
+
+	for (limit = addr + size; addr < limit; addr++) {
+		findjsobjects_instance_t *inst;
+		findjsobjects_obj_t *obj;
+		avl_index_t where;
+
+		if (V8_IS_SMI(addr))
+			continue;
+
+		if (!V8_IS_HEAPOBJECT(addr))
+			continue;
+
+		stats->fjss_heapobjs++;
+
+		mapaddr = *((uintptr_t *)((uintptr_t)range +
+		    (addr - base) + V8_OFF_HEAPOBJECT_MAP));
+
+		if (!V8_IS_HEAPOBJECT(mapaddr))
+			continue;
+
+		mapaddr += V8_OFF_MAP_INSTANCE_ATTRIBUTES;
+		stats->fjss_typereads++;
+
+		if (mapaddr >= base && mapaddr < base + size) {
+			stats->fjss_cached++;
+
+			type = *((uint8_t *)((uintptr_t)range +
+			    (mapaddr - base)));
+		} else {
+			if (mdb_vread(&type, sizeof (uint8_t), mapaddr) == -1)
+				continue;
+		}
+
+		if (type != jsobject && type != jsarray)
+			continue;
+
+		stats->fjss_jsobjs++;
+
+		fjs->fjs_current = findjsobjects_alloc(addr);
+
+		if (type == jsobject) {
+			if (jsobj_properties(addr,
+			    findjsobjects_prop, fjs) != 0) {
+				findjsobjects_free(fjs->fjs_current);
+				fjs->fjs_current = NULL;
+				continue;
+			}
+
+			findjsobjects_constructor(fjs->fjs_current);
+			stats->fjss_objects++;
+		} else {
+			uintptr_t ptr;
+			size_t *nprops = &fjs->fjs_current->fjso_nprops;
+			ssize_t len = V8_OFF_JSARRAY_LENGTH;
+			ssize_t elems = V8_OFF_JSOBJECT_ELEMENTS;
+			ssize_t flen = V8_OFF_FIXEDARRAY_LENGTH;
+			uintptr_t nelems;
+			uint8_t t;
+
+			if (read_heap_smi(nprops, addr, len) != 0 ||
+			    read_heap_ptr(&ptr, addr, elems) != 0 ||
+			    !V8_IS_HEAPOBJECT(ptr) ||
+			    read_typebyte(&t, ptr) != 0 ||
+			    t != V8_TYPE_FIXEDARRAY ||
+			    read_heap_smi(&nelems, ptr, flen) != 0 ||
+			    nelems < *nprops) {
+				findjsobjects_free(fjs->fjs_current);
+				fjs->fjs_current = NULL;
+				continue;
+			}
+
+			strcpy(fjs->fjs_current->fjso_constructor, "Array");
+			stats->fjss_arrays++;
+		}
+
+		/*
+		 * Now determine if we already have an object matching our
+		 * properties.  If we don't, we'll add our new object; if we
+		 * do we'll merely enqueue our instance.
+		 */
+		obj = avl_find(&fjs->fjs_tree, fjs->fjs_current, &where);
+
+		if (obj == NULL) {
+			avl_add(&fjs->fjs_tree, fjs->fjs_current);
+			fjs->fjs_current->fjso_next = fjs->fjs_objects;
+			fjs->fjs_objects = fjs->fjs_current;
+			fjs->fjs_current = NULL;
+			stats->fjss_uniques++;
+			continue;
+		}
+
+		findjsobjects_free(fjs->fjs_current);
+		fjs->fjs_current = NULL;
+
+		inst = mdb_alloc(sizeof (findjsobjects_instance_t), UM_SLEEP);
+		inst->fjsi_addr = addr;
+		inst->fjsi_next = obj->fjso_instances.fjsi_next;
+		obj->fjso_instances.fjsi_next = inst;
+		obj->fjso_ninstances++;
+	}
+
+	mdb_free(range, size);
+
+	return (0);
+}
+
+static int
+findjsobjects_mapping(findjsobjects_state_t *fjs, const prmap_t *pmp,
+    const char *name)
+{
+	if (name != NULL && !(fjs->fjs_brk && (pmp->pr_mflags & MA_BREAK)))
+		return (0);
+
+	if (fjs->fjs_addr != NULL && (fjs->fjs_addr < pmp->pr_vaddr ||
+	    fjs->fjs_addr >= pmp->pr_vaddr + pmp->pr_size))
+		return (0);
+
+	return (findjsobjects_range(fjs, pmp->pr_vaddr, pmp->pr_size));
+}
+
+static void
+findjsobjects_references_add(findjsobjects_state_t *fjs, uintptr_t val,
+    const char *desc, size_t index)
+{
+	findjsobjects_referent_t search, *referent;
+	findjsobjects_reference_t *reference;
+
+	search.fjsr_addr = val;
+
+	if ((referent = avl_find(&fjs->fjs_referents, &search, NULL)) == NULL)
+		return;
+
+	reference = mdb_zalloc(sizeof (*reference), UM_SLEEP | UM_GC);
+	reference->fjsrf_addr = fjs->fjs_addr;
+
+	if (desc != NULL) {
+		reference->fjsrf_desc =
+		    mdb_alloc(strlen(desc) + 1, UM_SLEEP | UM_GC);
+		(void) strcpy(reference->fjsrf_desc, desc);
+	} else {
+		reference->fjsrf_index = index;
+	}
+
+	if (referent->fjsr_head == NULL) {
+		referent->fjsr_head = reference;
+	} else {
+		referent->fjsr_tail->fjsrf_next = reference;
+	}
+
+	referent->fjsr_tail = reference;
+}
+
+static int
+findjsobjects_references_prop(const char *desc, uintptr_t val, void *arg)
+{
+	findjsobjects_references_add(arg, val, desc, -1);
+
+	return (0);
+}
+
+static void
+findjsobjects_references_array(findjsobjects_state_t *fjs,
+    findjsobjects_obj_t *obj)
+{
+	findjsobjects_instance_t *inst = &obj->fjso_instances;
+	uintptr_t *elts;
+	size_t i, len;
+
+	for (; inst != NULL; inst = inst->fjsi_next) {
+		uintptr_t addr = inst->fjsi_addr, ptr;
+
+		if (read_heap_ptr(&ptr, addr, V8_OFF_JSOBJECT_ELEMENTS) != 0 ||
+		    read_heap_array(ptr, &elts, &len, UM_SLEEP) != 0)
+			continue;
+
+		fjs->fjs_addr = addr;
+
+		for (i = 0; i < len; i++)
+			findjsobjects_references_add(fjs, elts[i], NULL, i);
+
+		mdb_free(elts, len * sizeof (uintptr_t));
+	}
+}
+
+static void
+findjsobjects_referent(findjsobjects_state_t *fjs, uintptr_t addr)
+{
+	findjsobjects_referent_t search, *referent;
+
+	search.fjsr_addr = addr;
+
+	if (avl_find(&fjs->fjs_referents, &search, NULL) != NULL) {
+		assert(fjs->fjs_marking);
+		mdb_warn("%p is already marked; ignoring\n", addr);
+		return;
+	}
+
+	referent = mdb_zalloc(sizeof (findjsobjects_referent_t), UM_SLEEP);
+	referent->fjsr_addr = addr;
+
+	avl_add(&fjs->fjs_referents, referent);
+
+	if (fjs->fjs_tail != NULL) {
+		fjs->fjs_tail->fjsr_next = referent;
+	} else {
+		fjs->fjs_head = referent;
+	}
+
+	fjs->fjs_tail = referent;
+
+	if (fjs->fjs_marking)
+		mdb_printf("findjsobjects: marked %p\n", addr);
+}
+
+static void
+findjsobjects_references(findjsobjects_state_t *fjs)
+{
+	findjsobjects_reference_t *reference;
+	findjsobjects_referent_t *referent;
+	avl_tree_t *referents = &fjs->fjs_referents;
+	findjsobjects_obj_t *obj;
+	void *cookie = NULL;
+	uintptr_t addr;
+
+	fjs->fjs_referred = B_FALSE;
+
+	v8_silent++;
+
+	/*
+	 * First traverse over all objects and arrays, looking for references
+	 * to our designated referent(s).
+	 */
+	for (obj = fjs->fjs_objects; obj != NULL; obj = obj->fjso_next) {
+		findjsobjects_instance_t *head = &obj->fjso_instances, *inst;
+
+		if (obj->fjso_nprops != 0 && obj->fjso_props == NULL) {
+			findjsobjects_references_array(fjs, obj);
+			continue;
+		}
+
+		for (inst = head; inst != NULL; inst = inst->fjsi_next) {
+			fjs->fjs_addr = inst->fjsi_addr;
+
+			(void) jsobj_properties(inst->fjsi_addr,
+			    findjsobjects_references_prop, fjs);
+		}
+	}
+
+	v8_silent--;
+	fjs->fjs_addr = NULL;
+
+	/*
+	 * Now go over our referent(s), reporting any references that we have
+	 * accumulated.
+	 */
+	for (referent = fjs->fjs_head; referent != NULL;
+	    referent = referent->fjsr_next) {
+		addr = referent->fjsr_addr;
+
+		if ((reference = referent->fjsr_head) == NULL) {
+			mdb_printf("%p is not referred to by a "
+			    "known object.\n", addr);
+			continue;
+		}
+
+		for (; reference != NULL; reference = reference->fjsrf_next) {
+			mdb_printf("%p referred to by %p",
+			    addr, reference->fjsrf_addr);
+
+			if (reference->fjsrf_desc == NULL) {
+				mdb_printf("[%d]\n", reference->fjsrf_index);
+			} else {
+				mdb_printf(".%s\n", reference->fjsrf_desc);
+			}
+		}
+	}
+
+	/*
+	 * Finally, destroy our referent nodes.
+	 */
+	while ((referent = avl_destroy_nodes(referents, &cookie)) != NULL)
+		mdb_free(referent, sizeof (findjsobjects_referent_t));
+
+	fjs->fjs_head = NULL;
+	fjs->fjs_tail = NULL;
+}
+
+static findjsobjects_instance_t *
+findjsobjects_instance(findjsobjects_state_t *fjs, uintptr_t addr,
+    findjsobjects_instance_t **headp)
+{
+	findjsobjects_obj_t *obj;
+
+	for (obj = fjs->fjs_objects; obj != NULL; obj = obj->fjso_next) {
+		findjsobjects_instance_t *head = &obj->fjso_instances, *inst;
+
+		for (inst = head; inst != NULL; inst = inst->fjsi_next) {
+			if (inst->fjsi_addr == addr) {
+				*headp = head;
+				return (inst);
+			}
+		}
+	}
+
+	return (NULL);
+}
+
+/*ARGSUSED*/
+static void
+findjsobjects_match_all(findjsobjects_obj_t *obj, const char *ignored)
+{
+	mdb_printf("%p\n", obj->fjso_instances.fjsi_addr);
+}
+
+static void
+findjsobjects_match_propname(findjsobjects_obj_t *obj, const char *propname)
+{
+	findjsobjects_prop_t *prop;
+
+	for (prop = obj->fjso_props; prop != NULL; prop = prop->fjsp_next) {
+		if (strcmp(prop->fjsp_desc, propname) == 0) {
+			mdb_printf("%p\n", obj->fjso_instances.fjsi_addr);
+			return;
+		}
+	}
+}
+
+static void
+findjsobjects_match_constructor(findjsobjects_obj_t *obj,
+    const char *constructor)
+{
+	if (strcmp(constructor, obj->fjso_constructor) == 0)
+		mdb_printf("%p\n", obj->fjso_instances.fjsi_addr);
+}
+
+static int
+findjsobjects_match(findjsobjects_state_t *fjs, uintptr_t addr,
+    uint_t flags, void (*func)(findjsobjects_obj_t *, const char *),
+    const char *match)
+{
+	findjsobjects_obj_t *obj;
+
+	if (!(flags & DCMD_ADDRSPEC)) {
+		for (obj = fjs->fjs_objects; obj != NULL;
+		    obj = obj->fjso_next) {
+			if (obj->fjso_malformed && !fjs->fjs_allobjs)
+				continue;
+
+			func(obj, match);
+		}
+
+		return (DCMD_OK);
+	}
+
+	/*
+	 * First, look for the specified address among the representative
+	 * objects.
+	 */
+	for (obj = fjs->fjs_objects; obj != NULL; obj = obj->fjso_next) {
+		if (obj->fjso_instances.fjsi_addr == addr) {
+			func(obj, match);
+			return (DCMD_OK);
+		}
+	}
+
+	/*
+	 * We didn't find it among the representative objects; iterate over
+	 * all objects.
+	 */
+	for (obj = fjs->fjs_objects; obj != NULL; obj = obj->fjso_next) {
+		findjsobjects_instance_t *head = &obj->fjso_instances, *inst;
+
+		for (inst = head; inst != NULL; inst = inst->fjsi_next) {
+			if (inst->fjsi_addr == addr) {
+				func(obj, match);
+				return (DCMD_OK);
+			}
+		}
+	}
+
+	mdb_warn("%p does not correspond to a known object\n", addr);
+	return (DCMD_ERR);
+}
+
+static void
+findjsobjects_print(findjsobjects_obj_t *obj)
+{
+	int col = 19 + (sizeof (uintptr_t) * 2) + strlen("..."), len;
+	uintptr_t addr = obj->fjso_instances.fjsi_addr;
+	findjsobjects_prop_t *prop;
+
+	mdb_printf("%?p %8d %8d ",
+	    addr, obj->fjso_ninstances, obj->fjso_nprops);
+
+	if (obj->fjso_constructor[0] != '\0') {
+		mdb_printf("%s%s", obj->fjso_constructor,
+		    obj->fjso_props != NULL ? ": " : "");
+		col += strlen(obj->fjso_constructor) + 2;
+	}
+
+	for (prop = obj->fjso_props; prop != NULL; prop = prop->fjsp_next) {
+		if (col + (len = strlen(prop->fjsp_desc) + 2) < 80) {
+			mdb_printf("%s%s", prop->fjsp_desc,
+			    prop->fjsp_next != NULL ? ", " : "");
+			col += len;
+		} else {
+			mdb_printf("...");
+			break;
+		}
+	}
+
+	mdb_printf("\n", col);
+}
+
+static void
+dcmd_findjsobjects_help(void)
+{
+	mdb_printf("%s\n\n",
+"Finds all JavaScript objects in the V8 heap via brute force iteration over\n"
+"all mapped anonymous memory.  (This can take up to several minutes on large\n"
+"dumps.)  The output consists of representative objects, the number of\n"
+"instances of that object and the number of properties on the object --\n"
+"followed by the constructor and first few properties of the objects.  Once\n"
+"run, subsequent calls to ::findjsobjects use cached data.  If provided an\n"
+"address (and in the absence of -r, described below), ::findjsobjects treats\n"
+"the address as that of a representative object, and lists all instances of\n"
+"that object (that is, all objects that have a matching property signature).");
+
+	mdb_dec_indent(2);
+	mdb_printf("%<b>OPTIONS%</b>\n");
+	mdb_inc_indent(2);
+
+	mdb_printf("%s\n",
+"  -b       Include the heap denoted by the brk(2) (normally excluded)\n"
+"  -c cons  Display representative objects with the specified constructor\n"
+"  -p prop  Display representative objects that have the specified property\n"
+"  -l       List all objects that match the representative object\n"
+"  -m       Mark specified object for later reference determination via -r\n"
+"  -r       Find references to the specified and/or marked object(s)\n"
+"  -v       Provide verbose statistics\n");
+}
+
+static int
+dcmd_findjsobjects(uintptr_t addr,
+    uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	static findjsobjects_state_t fjs;
+	static findjsobjects_stats_t *stats = &fjs.fjs_stats;
+	findjsobjects_obj_t *obj;
+	struct ps_prochandle *Pr;
+	boolean_t references = B_FALSE, listlike = B_FALSE;
+	const char *propname = NULL;
+	const char *constructor = NULL;
+
+	fjs.fjs_verbose = B_FALSE;
+	fjs.fjs_brk = B_FALSE;
+	fjs.fjs_marking = B_FALSE;
+	fjs.fjs_allobjs = B_FALSE;
+
+	if (mdb_getopts(argc, argv,
+	    'a', MDB_OPT_SETBITS, B_TRUE, &fjs.fjs_allobjs,
+	    'b', MDB_OPT_SETBITS, B_TRUE, &fjs.fjs_brk,
+	    'c', MDB_OPT_STR, &constructor,
+	    'l', MDB_OPT_SETBITS, B_TRUE, &listlike,
+	    'm', MDB_OPT_SETBITS, B_TRUE, &fjs.fjs_marking,
+	    'p', MDB_OPT_STR, &propname,
+	    'r', MDB_OPT_SETBITS, B_TRUE, &references,
+	    'v', MDB_OPT_SETBITS, B_TRUE, &fjs.fjs_verbose,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	if (!fjs.fjs_initialized) {
+		avl_create(&fjs.fjs_tree,
+		    (int(*)(const void *, const void *))findjsobjects_cmp,
+		    sizeof (findjsobjects_obj_t),
+		    offsetof(findjsobjects_obj_t, fjso_node));
+
+		avl_create(&fjs.fjs_referents,
+		    (int(*)(const void *, const void *))
+		    findjsobjects_cmp_referents,
+		    sizeof (findjsobjects_referent_t),
+		    offsetof(findjsobjects_referent_t, fjsr_node));
+
+		fjs.fjs_initialized = B_TRUE;
+	}
+
+	if (avl_is_empty(&fjs.fjs_tree)) {
+		findjsobjects_obj_t **sorted;
+		int nobjs, i;
+		hrtime_t start = gethrtime();
+
+		if (mdb_get_xdata("pshandle", &Pr, sizeof (Pr)) == -1) {
+			mdb_warn("couldn't read pshandle xdata");
+			return (DCMD_ERR);
+		}
+
+		v8_silent++;
+
+		if (Pmapping_iter(Pr,
+		    (proc_map_f *)findjsobjects_mapping, &fjs) != 0) {
+			v8_silent--;
+			return (DCMD_ERR);
+		}
+
+		if ((nobjs = avl_numnodes(&fjs.fjs_tree)) != 0) {
+			/*
+			 * We have the objects -- now sort them.
+			 */
+			sorted = mdb_alloc(nobjs * sizeof (void *),
+			    UM_SLEEP | UM_GC);
+
+			for (obj = fjs.fjs_objects, i = 0; obj != NULL;
+			    obj = obj->fjso_next, i++) {
+				sorted[i] = obj;
+			}
+
+			qsort(sorted, avl_numnodes(&fjs.fjs_tree),
+			    sizeof (void *), findjsobjects_cmp_ninstances);
+
+			for (i = 1, fjs.fjs_objects = sorted[0]; i < nobjs; i++)
+				sorted[i - 1]->fjso_next = sorted[i];
+
+			sorted[nobjs - 1]->fjso_next = NULL;
+		}
+
+		v8_silent--;
+
+		if (fjs.fjs_verbose) {
+			const char *f = "findjsobjects: %30s => %d\n";
+			int elapsed = (int)((gethrtime() - start) / NANOSEC);
+
+			mdb_printf(f, "elapsed time (seconds)", elapsed);
+			mdb_printf(f, "heap objects", stats->fjss_heapobjs);
+			mdb_printf(f, "type reads", stats->fjss_typereads);
+			mdb_printf(f, "cached reads", stats->fjss_cached);
+			mdb_printf(f, "JavaScript objects", stats->fjss_jsobjs);
+			mdb_printf(f, "processed objects", stats->fjss_objects);
+			mdb_printf(f, "processed arrays", stats->fjss_arrays);
+			mdb_printf(f, "unique objects", stats->fjss_uniques);
+		}
+	}
+
+	if (listlike && !(flags & DCMD_ADDRSPEC)) {
+		if (propname != NULL || constructor != NULL) {
+			char opt = propname != NULL ? 'p' : 'c';
+
+			mdb_warn("cannot specify -l with -%c; instead, pipe "
+			    "output of ::findjsobjects -%c to "
+			    "::findjsobjects -l\n", opt, opt);
+			return (DCMD_ERR);
+		}
+
+		return (findjsobjects_match(&fjs, addr, flags,
+		    findjsobjects_match_all, NULL));
+	}
+
+	if (propname != NULL) {
+		if (constructor != NULL) {
+			mdb_warn("cannot specify both a property name "
+			    "and a constructor\n");
+			return (DCMD_ERR);
+		}
+
+		return (findjsobjects_match(&fjs, addr, flags,
+		    findjsobjects_match_propname, propname));
+	}
+
+	if (constructor != NULL) {
+		return (findjsobjects_match(&fjs, addr, flags,
+		    findjsobjects_match_constructor, constructor));
+	}
+
+	if (references && !(flags & DCMD_ADDRSPEC) &&
+	    avl_is_empty(&fjs.fjs_referents)) {
+		mdb_warn("must specify or mark an object to find references\n");
+		return (DCMD_ERR);
+	}
+
+	if (fjs.fjs_marking && !(flags & DCMD_ADDRSPEC)) {
+		mdb_warn("must specify an object to mark\n");
+		return (DCMD_ERR);
+	}
+
+	if (references && fjs.fjs_marking) {
+		mdb_warn("can't both mark an object and find its references\n");
+		return (DCMD_ERR);
+	}
+
+	if (flags & DCMD_ADDRSPEC) {
+		findjsobjects_instance_t *inst, *head;
+
+		/*
+		 * If we've been passed an address, it's to either list like
+		 * objects (-l), mark an object (-m) or find references to the
+		 * specified/marked objects (-r).  (Note that the absence of
+		 * any of these options implies -l.)
+		 */
+		inst = findjsobjects_instance(&fjs, addr, &head);
+
+		if (inst == NULL) {
+			mdb_warn("%p is not a valid object\n", addr);
+			return (DCMD_ERR);
+		}
+
+		if (!references && !fjs.fjs_marking) {
+			for (inst = head; inst != NULL; inst = inst->fjsi_next)
+				mdb_printf("%p\n", inst->fjsi_addr);
+
+			return (DCMD_OK);
+		}
+
+		if (!listlike) {
+			findjsobjects_referent(&fjs, inst->fjsi_addr);
+		} else {
+			for (inst = head; inst != NULL; inst = inst->fjsi_next)
+				findjsobjects_referent(&fjs, inst->fjsi_addr);
+		}
+	}
+
+	if (references)
+		findjsobjects_references(&fjs);
+
+	if (references || fjs.fjs_marking)
+		return (DCMD_OK);
+
+	mdb_printf("%?s %8s %8s %s\n", "OBJECT",
+	    "#OBJECTS", "#PROPS", "CONSTRUCTOR: PROPS");
+
+	for (obj = fjs.fjs_objects; obj != NULL; obj = obj->fjso_next) {
+		if (obj->fjso_malformed && !fjs.fjs_allobjs)
+			continue;
+
+		findjsobjects_print(obj);
+	}
+
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_jsframe(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	uintptr_t fptr, raddr;
+	boolean_t opt_v = B_FALSE, opt_i = B_FALSE;
+	char *opt_f = NULL, *opt_p = NULL;
+
+	if (mdb_getopts(argc, argv,
+	    'v', MDB_OPT_SETBITS, B_TRUE, &opt_v,
+	    'i', MDB_OPT_SETBITS, B_TRUE, &opt_i,
+	    'f', MDB_OPT_STR, &opt_f,
+	    'p', MDB_OPT_STR, &opt_p, NULL) != argc)
+		return (DCMD_USAGE);
+
+	/*
+	 * As with $C, we assume we are given a *pointer* to the frame pointer
+	 * for a frame, rather than the actual frame pointer for the frame of
+	 * interest. This is needed to show the instruction pointer, which is
+	 * actually stored with the next frame.  For debugging, this can be
+	 * overridden with the "-i" option (for "immediate").
+	 */
+	if (opt_i)
+		return (do_jsframe(addr, 0, opt_v, opt_f, opt_p));
+
+	if (mdb_vread(&raddr, sizeof (raddr),
+	    addr + sizeof (uintptr_t)) == -1) {
+		mdb_warn("failed to read return address from %p",
+		    addr + sizeof (uintptr_t));
+		return (DCMD_ERR);
+	}
+
+	if (mdb_vread(&fptr, sizeof (fptr), addr) == -1) {
+		mdb_warn("failed to read frame pointer from %p", addr);
+		return (DCMD_ERR);
+	}
+
+	if (fptr == NULL)
+		return (DCMD_OK);
+
+	return (do_jsframe(fptr, raddr, opt_v, opt_f, opt_p));
+}
+
+/* ARGSUSED */
+static int
+dcmd_jsprint(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	char *buf, *bufp;
+	size_t bufsz = 262144, len = bufsz;
+	jsobj_print_t jsop;
+	boolean_t opt_b = B_FALSE;
+	int rv, i;
+
+	bzero(&jsop, sizeof (jsop));
+	jsop.jsop_depth = 2;
+	jsop.jsop_printaddr = B_FALSE;
+
+	i = mdb_getopts(argc, argv,
+	    'a', MDB_OPT_SETBITS, B_TRUE, &jsop.jsop_printaddr,
+	    'b', MDB_OPT_SETBITS, B_TRUE, &opt_b,
+	    'd', MDB_OPT_UINT64, &jsop.jsop_depth, NULL);
+
+	if (opt_b)
+		jsop.jsop_baseaddr = addr;
+
+	do {
+		if (i != argc) {
+			const mdb_arg_t *member = &argv[i++];
+
+			if (member->a_type != MDB_TYPE_STRING)
+				return (DCMD_USAGE);
+
+			jsop.jsop_member = member->a_un.a_str;
+		}
+
+		for (;;) {
+			if ((buf = bufp =
+			    mdb_zalloc(bufsz, UM_NOSLEEP)) == NULL)
+				return (DCMD_ERR);
+
+			jsop.jsop_bufp = &bufp;
+			jsop.jsop_lenp = &len;
+
+			rv = jsobj_print(addr, &jsop);
+
+			if (len > 0)
+				break;
+
+			mdb_free(buf, bufsz);
+			bufsz <<= 1;
+			len = bufsz;
+		}
+
+		if (jsop.jsop_member == NULL && rv != 0)
+			return (DCMD_ERR);
+
+		if (jsop.jsop_member && !jsop.jsop_found) {
+			if (jsop.jsop_baseaddr)
+				(void) mdb_printf("%p: ", jsop.jsop_baseaddr);
+
+			(void) mdb_printf("undefined%s",
+			    i < argc ? " " : "");
+		} else {
+			(void) mdb_printf("%s%s", buf, i < argc &&
+			    !isspace(buf[strlen(buf) - 1]) ? " " : "");
+		}
+
+		mdb_free(buf, bufsz);
+		jsop.jsop_found = B_FALSE;
+		jsop.jsop_baseaddr = NULL;
+	} while (i < argc);
+
+	mdb_printf("\n");
+
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8field(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	v8_class_t *clp;
+	v8_field_t *flp;
+	const char *klass, *field;
+	uintptr_t offset = 0;
+
+	/*
+	 * We may be invoked with either two arguments (class and field name) or
+	 * three (an offset to save).
+	 */
+	if (argc != 2 && argc != 3)
+		return (DCMD_USAGE);
+
+	if (argv[0].a_type != MDB_TYPE_STRING ||
+	    argv[1].a_type != MDB_TYPE_STRING)
+		return (DCMD_USAGE);
+
+	klass = argv[0].a_un.a_str;
+	field = argv[1].a_un.a_str;
+
+	if (argc == 3) {
+		if (argv[2].a_type != MDB_TYPE_STRING)
+			return (DCMD_USAGE);
+
+		offset = mdb_strtoull(argv[2].a_un.a_str);
+	}
+
+	for (clp = v8_classes; clp != NULL; clp = clp->v8c_next)
+		if (strcmp(clp->v8c_name, klass) == 0)
+			break;
+
+	if (clp == NULL) {
+		(void) mdb_printf("error: no such class: \"%s\"", klass);
+		return (DCMD_ERR);
+	}
+
+	for (flp = clp->v8c_fields; flp != NULL; flp = flp->v8f_next)
+		if (strcmp(field, flp->v8f_name) == 0)
+			break;
+
+	if (flp == NULL) {
+		if (argc == 2) {
+			mdb_printf("error: no such field in class \"%s\": "
+			    "\"%s\"", klass, field);
+			return (DCMD_ERR);
+		}
+
+		flp = conf_field_create(clp, field, offset);
+		if (flp == NULL) {
+			mdb_warn("failed to create field");
+			return (DCMD_ERR);
+		}
+	} else if (argc == 3) {
+		flp->v8f_offset = offset;
+	}
+
+	mdb_printf("%s::%s at offset 0x%x\n", klass, field, flp->v8f_offset);
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8array(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	uint8_t type;
+	uintptr_t *array;
+	size_t ii, len;
+
+	if (read_typebyte(&type, addr) != 0)
+		return (DCMD_ERR);
+
+	if (type != V8_TYPE_FIXEDARRAY) {
+		mdb_warn("%p is not an instance of FixedArray\n", addr);
+		return (DCMD_ERR);
+	}
+
+	if (read_heap_array(addr, &array, &len, UM_SLEEP | UM_GC) != 0)
+		return (DCMD_ERR);
+
+	for (ii = 0; ii < len; ii++)
+		mdb_printf("%p\n", array[ii]);
+
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_jsstack(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	uintptr_t raddr;
+	boolean_t opt_v;
+	char *opt_f = NULL, *opt_p = NULL;
+
+	if (mdb_getopts(argc, argv,
+	    'v', MDB_OPT_SETBITS, B_TRUE, &opt_v,
+	    'f', MDB_OPT_STR, &opt_f,
+	    'p', MDB_OPT_STR, &opt_p,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	/*
+	 * The "::jsframe" walker iterates the valid frame pointers, but the
+	 * "::jsframe" dcmd looks at the frame after the one it was given, so we
+	 * have to explicitly examine the top frame here.
+	 */
+	if (!(flags & DCMD_ADDRSPEC)) {
+		if (load_current_context(&addr, &raddr) != 0 ||
+		    do_jsframe(addr, raddr, opt_v, opt_f, opt_p) != 0)
+			return (DCMD_ERR);
+	}
+
+	if (mdb_pwalk_dcmd("jsframe", "jsframe", argc, argv, addr) == -1)
+		return (DCMD_ERR);
+
+	return (DCMD_OK);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8str(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	boolean_t opt_v = B_FALSE;
+	char buf[512 * 1024];
+	char *bufp;
+	size_t len;
+
+	if (mdb_getopts(argc, argv, 'v', MDB_OPT_SETBITS, B_TRUE, &opt_v,
+	    NULL) != argc)
+		return (DCMD_USAGE);
+
+	bufp = buf;
+	len = sizeof (buf);
+	if (jsstr_print(addr, (opt_v ? JSSTR_VERBOSE : JSSTR_NONE) |
+	    JSSTR_QUOTED, &bufp, &len) != 0)
+		return (DCMD_ERR);
+
+	mdb_printf("%s\n", buf);
+	return (DCMD_OK);
+}
+
+static void
+dcmd_v8load_help(void)
+{
+	v8_cfg_t *cfp, **cfgpp;
+
+	mdb_printf(
+	    "To traverse in-memory V8 structures, the V8 dmod requires\n"
+	    "configuration that describes the layout of various V8 structures\n"
+	    "in memory.  Normally, this information is pulled from metadata\n"
+	    "in the target binary.  However, it's possible to use the module\n"
+	    "with a binary not built with metadata by loading one of the\n"
+	    "canned configurations.\n\n");
+
+	mdb_printf("Available configurations:\n");
+
+	(void) mdb_inc_indent(4);
+
+	for (cfgpp = v8_cfgs; *cfgpp != NULL; cfgpp++) {
+		cfp = *cfgpp;
+		mdb_printf("%-10s    %s\n", cfp->v8cfg_name, cfp->v8cfg_label);
+	}
+
+	(void) mdb_dec_indent(4);
+}
+
+/* ARGSUSED */
+static int
+dcmd_v8load(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
+{
+	v8_cfg_t *cfgp = NULL, **cfgpp;
+
+	if (v8_classes != NULL) {
+		mdb_warn("v8 module already configured\n");
+		return (DCMD_ERR);
+	}
+
+	if (argc < 1 || argv->a_type != MDB_TYPE_STRING)
+		return (DCMD_USAGE);
+
+	for (cfgpp = v8_cfgs; *cfgpp != NULL; cfgpp++) {
+		cfgp = *cfgpp;
+		if (strcmp(argv->a_un.a_str, cfgp->v8cfg_name) == 0)
+			break;
+	}
+
+	if (cfgp == NULL || cfgp->v8cfg_name == NULL) {
+		mdb_warn("unknown configuration: \"%s\"\n", argv->a_un.a_str);
+		return (DCMD_ERR);
+	}
+
+	if (autoconfigure(cfgp) == -1) {
+		mdb_warn("autoconfigure failed\n");
+		return (DCMD_ERR);
+	}
+
+	mdb_printf("V8 dmod configured based on %s\n", cfgp->v8cfg_name);
+	return (DCMD_OK);
+}
+
+static int
+walk_jsframes_init(mdb_walk_state_t *wsp)
+{
+	if (wsp->walk_addr != NULL)
+		return (WALK_NEXT);
+
+	if (load_current_context(&wsp->walk_addr, NULL) != 0)
+		return (WALK_ERR);
+
+	return (WALK_NEXT);
+}
+
+static int
+walk_jsframes_step(mdb_walk_state_t *wsp)
+{
+	uintptr_t addr, next;
+	int rv;
+
+	addr = wsp->walk_addr;
+	rv = wsp->walk_callback(wsp->walk_addr, NULL, wsp->walk_cbdata);
+
+	if (rv != WALK_NEXT)
+		return (rv);
+
+	if (mdb_vread(&next, sizeof (next), addr) == -1)
+		return (WALK_ERR);
+
+	if (next == NULL)
+		return (WALK_DONE);
+
+	wsp->walk_addr = next;
+	return (WALK_NEXT);
+}
+
+typedef struct jsprop_walk_data {
+	int jspw_nprops;
+	int jspw_current;
+	uintptr_t *jspw_props;
+} jsprop_walk_data_t;
+
+/*ARGSUSED*/
+static int
+walk_jsprop_nprops(const char *desc, uintptr_t val, void *arg)
+{
+	jsprop_walk_data_t *jspw = arg;
+	jspw->jspw_nprops++;
+
+	return (0);
+}
+
+/*ARGSUSED*/
+static int
+walk_jsprop_props(const char *desc, uintptr_t val, void *arg)
+{
+	jsprop_walk_data_t *jspw = arg;
+	jspw->jspw_props[jspw->jspw_current++] = val;
+
+	return (0);
+}
+
+static int
+walk_jsprop_init(mdb_walk_state_t *wsp)
+{
+	jsprop_walk_data_t *jspw;
+	uintptr_t addr;
+	uint8_t type;
+
+	if ((addr = wsp->walk_addr) == NULL) {
+		mdb_warn("'jsprop' does not support global walks\n");
+		return (WALK_ERR);
+	}
+
+	if (!V8_IS_HEAPOBJECT(addr) || read_typebyte(&type, addr) != 0 ||
+	    type != V8_TYPE_JSOBJECT) {
+		mdb_warn("%p is not a JSObject\n", addr);
+		return (WALK_ERR);
+	}
+
+	jspw = mdb_zalloc(sizeof (jsprop_walk_data_t), UM_SLEEP | UM_GC);
+
+	if (jsobj_properties(addr, walk_jsprop_nprops, jspw) == -1) {
+		mdb_warn("couldn't iterate over properties for %p\n", addr);
+		return (WALK_ERR);
+	}
+
+	jspw->jspw_props = mdb_zalloc(jspw->jspw_nprops *
+	    sizeof (uintptr_t), UM_SLEEP | UM_GC);
+
+	if (jsobj_properties(addr, walk_jsprop_props, jspw) == -1) {
+		mdb_warn("couldn't iterate over properties for %p\n", addr);
+		return (WALK_ERR);
+	}
+
+	jspw->jspw_current = 0;
+	wsp->walk_data = jspw;
+
+	return (WALK_NEXT);
+}
+
+static int
+walk_jsprop_step(mdb_walk_state_t *wsp)
+{
+	jsprop_walk_data_t *jspw = wsp->walk_data;
+	int rv;
+
+	if (jspw->jspw_current >= jspw->jspw_nprops)
+		return (WALK_DONE);
+
+	if ((rv = wsp->walk_callback(jspw->jspw_props[jspw->jspw_current++],
+	    NULL, wsp->walk_cbdata)) != WALK_NEXT)
+		return (rv);
+
+	return (WALK_NEXT);
+}
+
+/*
+ * MDB linkage
+ */
+
+static const mdb_dcmd_t v8_mdb_dcmds[] = {
+	/*
+	 * Commands to inspect JavaScript-level state
+	 */
+	{ "jsframe", ":[-iv] [-f function] [-p property]",
+		"summarize a JavaScript stack frame", dcmd_jsframe },
+	{ "jsprint", ":[-ab] [-d depth] [member]", "print a JavaScript object",
+		dcmd_jsprint },
+	{ "jsstack", "[-v] [-f function] [-p property]",
+		"print a JavaScript stacktrace", dcmd_jsstack },
+	{ "findjsobjects", "?[-vb] [-r | -c cons | -p prop]", "find JavaScript "
+		"objects", dcmd_findjsobjects, dcmd_findjsobjects_help },
+
+	/*
+	 * Commands to inspect V8-level state
+	 */
+	{ "v8array", ":", "print elements of a V8 FixedArray",
+		dcmd_v8array },
+	{ "v8classes", NULL, "list known V8 heap object C++ classes",
+		dcmd_v8classes },
+	{ "v8code", ":[-d]", "print information about a V8 Code object",
+		dcmd_v8code },
+	{ "v8field", "classname fieldname offset",
+		"manually add a field to a given class", dcmd_v8field },
+	{ "v8function", ":[-d]", "print JSFunction object details",
+		dcmd_v8function },
+	{ "v8load", "version", "load canned config for a specific V8 version",
+		dcmd_v8load, dcmd_v8load_help },
+	{ "v8frametypes", NULL, "list known V8 frame types",
+		dcmd_v8frametypes },
+	{ "v8print", ":[class]", "print a V8 heap object",
+		dcmd_v8print, dcmd_v8print_help },
+	{ "v8str", ":[-v]", "print the contents of a V8 string",
+		dcmd_v8str },
+	{ "v8type", ":", "print the type of a V8 heap object",
+		dcmd_v8type },
+	{ "v8types", NULL, "list known V8 heap object types",
+		dcmd_v8types },
+
+	{ NULL }
+};
+
+static const mdb_walker_t v8_mdb_walkers[] = {
+	{ "jsframe", "walk V8 JavaScript stack frames",
+		walk_jsframes_init, walk_jsframes_step },
+	{ "jsprop", "walk property values for an object",
+		walk_jsprop_init, walk_jsprop_step },
+	{ NULL }
+};
+
+static mdb_modinfo_t v8_mdb = { MDB_API_VERSION, v8_mdb_dcmds, v8_mdb_walkers };
+
+static void
+configure(void)
+{
+	char *success;
+	v8_cfg_t *cfgp = NULL;
+	GElf_Sym sym;
+
+	if (mdb_readsym(&v8_major, sizeof (v8_major),
+	    "_ZN2v88internal7Version6major_E") == -1 ||
+	    mdb_readsym(&v8_minor, sizeof (v8_minor),
+	    "_ZN2v88internal7Version6minor_E") == -1 ||
+	    mdb_readsym(&v8_build, sizeof (v8_build),
+	    "_ZN2v88internal7Version6build_E") == -1 ||
+	    mdb_readsym(&v8_patch, sizeof (v8_patch),
+	    "_ZN2v88internal7Version6patch_E") == -1) {
+		mdb_warn("failed to determine V8 version");
+		return;
+	}
+
+	mdb_printf("V8 version: %d.%d.%d.%d\n",
+	    v8_major, v8_minor, v8_build, v8_patch);
+
+	/*
+	 * First look for debug metadata embedded within the binary, which may
+	 * be present in recent V8 versions built with postmortem metadata.
+	 */
+	if (mdb_lookup_by_name("v8dbg_SmiTag", &sym) == 0) {
+		cfgp = &v8_cfg_target;
+		success = "Autoconfigured V8 support from target";
+	} else if (v8_major == 3 && v8_minor == 1 && v8_build == 8) {
+		cfgp = &v8_cfg_04;
+		success = "Configured V8 support based on node v0.4";
+	} else if (v8_major == 3 && v8_minor == 6 && v8_build == 6) {
+		cfgp = &v8_cfg_06;
+		success = "Configured V8 support based on node v0.6";
+	} else {
+		mdb_printf("mdb_v8: target has no debug metadata and "
+		    "no existing config found\n");
+		return;
+	}
+
+	if (autoconfigure(cfgp) != 0) {
+		mdb_warn("failed to autoconfigure from target; "
+		    "commands may have incorrect results!\n");
+		return;
+	}
+
+	mdb_printf("%s\n", success);
+}
+
+static void
+enable_demangling(void)
+{
+	const char *symname = "_ZN2v88internal7Version6major_E";
+	GElf_Sym sym;
+	char buf[64];
+
+	/*
+	 * Try to determine whether C++ symbol demangling has been enabled.  If
+	 * not, enable it.
+	 */
+	if (mdb_lookup_by_name("_ZN2v88internal7Version6major_E", &sym) != 0)
+		return;
+
+	(void) mdb_snprintf(buf, sizeof (buf), "%a", sym.st_value);
+	if (strstr(buf, symname) != NULL)
+		(void) mdb_eval("$G");
+}
+
+const mdb_modinfo_t *
+_mdb_init(void)
+{
+	configure();
+	enable_demangling();
+	return (&v8_mdb);
+}
diff --git a/deps/mdb_v8/mdb_v8.gyp b/deps/mdb_v8/mdb_v8.gyp
new file mode 100644
index 000000000..e7bb65992
--- /dev/null
+++ b/deps/mdb_v8/mdb_v8.gyp
@@ -0,0 +1,22 @@
+{
+  'targets': [
+    {
+      'target_name': 'mdb_v8',
+      'product_prefix': '',
+      'type': 'loadable_module',
+      'cflags': [ '-fPIC' ],
+      'sources': [
+        'mdb_v8.c',
+        'mdb_v8_cfg.c',
+        'v8cfg.h',
+        'v8dbg.h',
+      ],
+      'link_settings': {
+        'libraries': [
+          '-lproc',
+          '-lavl',
+        ],
+      },
+    },
+  ],
+}
diff --git a/deps/mdb_v8/mdb_v8_cfg.c b/deps/mdb_v8/mdb_v8_cfg.c
new file mode 100644
index 000000000..219b84f4f
--- /dev/null
+++ b/deps/mdb_v8/mdb_v8_cfg.c
@@ -0,0 +1,725 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * mdb_v8_cfg.c: canned configurations for previous V8 versions.
+ *
+ * The functions and data defined here enable this dmod to support debugging
+ * Node.js binaries that predated V8's built-in postmortem debugging support.
+ */
+
+#include "v8cfg.h"
+
+/*ARGSUSED*/
+static int
+v8cfg_target_iter(v8_cfg_t *cfgp, int (*func)(mdb_symbol_t *, void *),
+    void *arg)
+{
+	return (mdb_symbol_iter(MDB_OBJ_EVERY, MDB_DYNSYM,
+	    MDB_BIND_GLOBAL | MDB_TYPE_OBJECT | MDB_TYPE_FUNC,
+	    func, arg));
+}
+
+/*ARGSUSED*/
+static int
+v8cfg_target_readsym(v8_cfg_t *cfgp, const char *name, intptr_t *valp)
+{
+	int val, rval;
+
+	if ((rval = mdb_readsym(&val, sizeof (val), name)) != -1)
+		*valp = (intptr_t)val;
+
+	return (rval);
+}
+
+/*
+ * Analog of mdb_symbol_iter() for a canned configuration.
+ */
+static int
+v8cfg_canned_iter(v8_cfg_t *cfgp, int (*func)(mdb_symbol_t *, void *),
+    void *arg)
+{
+	v8_cfg_symbol_t *v8sym;
+	mdb_symbol_t mdbsym;
+	int rv;
+
+	for (v8sym = cfgp->v8cfg_symbols; v8sym->v8cs_name != NULL; v8sym++) {
+		mdbsym.sym_name = v8sym->v8cs_name;
+		mdbsym.sym_object = NULL;
+		mdbsym.sym_sym = NULL;
+		mdbsym.sym_table = 0;
+		mdbsym.sym_id = 0;
+
+		if ((rv = func(&mdbsym, arg)) != 0)
+			return (rv);
+	}
+
+	return (0);
+}
+
+/*
+ * Analog of mdb_readsym() for a canned configuration.
+ */
+static int
+v8cfg_canned_readsym(v8_cfg_t *cfgp, const char *name, intptr_t *valp)
+{
+	v8_cfg_symbol_t *v8sym;
+
+	for (v8sym = cfgp->v8cfg_symbols; v8sym->v8cs_name != NULL; v8sym++) {
+		if (strcmp(name, v8sym->v8cs_name) == 0)
+			break;
+	}
+
+	if (v8sym->v8cs_name == NULL)
+		return (-1);
+
+	*valp = v8sym->v8cs_value;
+	return (0);
+}
+
+/*
+ * Canned configuration for the V8 bundled with Node.js v0.4.8 and later.
+ */
+static v8_cfg_symbol_t v8_symbols_node_04[] = {
+	{ "v8dbg_type_AccessCheckInfo__ACCESS_CHECK_INFO_TYPE", 0x91 },
+	{ "v8dbg_type_AccessorInfo__ACCESSOR_INFO_TYPE", 0x90 },
+	{ "v8dbg_type_BreakPointInfo__BREAK_POINT_INFO_TYPE", 0x9b },
+	{ "v8dbg_type_ByteArray__BYTE_ARRAY_TYPE", 0x86 },
+	{ "v8dbg_type_CallHandlerInfo__CALL_HANDLER_INFO_TYPE", 0x93 },
+	{ "v8dbg_type_Code__CODE_TYPE", 0x81 },
+	{ "v8dbg_type_CodeCache__CODE_CACHE_TYPE", 0x99 },
+	{ "v8dbg_type_ConsString__CONS_ASCII_STRING_TYPE", 0x5 },
+	{ "v8dbg_type_ConsString__CONS_ASCII_SYMBOL_TYPE", 0x45 },
+	{ "v8dbg_type_ConsString__CONS_STRING_TYPE", 0x1 },
+	{ "v8dbg_type_ConsString__CONS_SYMBOL_TYPE", 0x41 },
+	{ "v8dbg_type_DebugInfo__DEBUG_INFO_TYPE", 0x9a },
+	{ "v8dbg_type_ExternalAsciiString__EXTERNAL_ASCII_STRING_TYPE", 0x6 },
+	{ "v8dbg_type_ExternalAsciiString__EXTERNAL_ASCII_SYMBOL_TYPE", 0x46 },
+	{ "v8dbg_type_ExternalByteArray__EXTERNAL_BYTE_ARRAY_TYPE", 0x88 },
+	{ "v8dbg_type_ExternalFloatArray__EXTERNAL_FLOAT_ARRAY_TYPE", 0x8e },
+	{ "v8dbg_type_ExternalIntArray__EXTERNAL_INT_ARRAY_TYPE", 0x8c },
+	{ "v8dbg_type_ExternalShortArray__EXTERNAL_SHORT_ARRAY_TYPE", 0x8a },
+	{ "v8dbg_type_ExternalString__EXTERNAL_STRING_TYPE", 0x2 },
+	{ "v8dbg_type_ExternalString__EXTERNAL_SYMBOL_TYPE", 0x42 },
+	{ "v8dbg_type_ExternalUnsignedByteArray__"
+		"EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE", 0x89 },
+	{ "v8dbg_type_ExternalUnsignedIntArray__"
+		"EXTERNAL_UNSIGNED_INT_ARRAY_TYPE", 0x8d },
+	{ "v8dbg_type_ExternalUnsignedShortArray__"
+		"EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE", 0x8b },
+	{ "v8dbg_type_FixedArray__FIXED_ARRAY_TYPE", 0x9c },
+	{ "v8dbg_type_FunctionTemplateInfo__"
+		"FUNCTION_TEMPLATE_INFO_TYPE", 0x94 },
+	{ "v8dbg_type_HeapNumber__HEAP_NUMBER_TYPE", 0x84 },
+	{ "v8dbg_type_InterceptorInfo__INTERCEPTOR_INFO_TYPE", 0x92 },
+	{ "v8dbg_type_JSArray__JS_ARRAY_TYPE", 0xa5 },
+	{ "v8dbg_type_JSBuiltinsObject__JS_BUILTINS_OBJECT_TYPE", 0xa3 },
+	{ "v8dbg_type_JSFunction__JS_FUNCTION_TYPE", 0xa7 },
+	{ "v8dbg_type_JSGlobalObject__JS_GLOBAL_OBJECT_TYPE", 0xa2 },
+	{ "v8dbg_type_JSGlobalPropertyCell__"
+		"JS_GLOBAL_PROPERTY_CELL_TYPE", 0x83 },
+	{ "v8dbg_type_JSGlobalProxy__JS_GLOBAL_PROXY_TYPE", 0xa4 },
+	{ "v8dbg_type_JSMessageObject__JS_MESSAGE_OBJECT_TYPE", 0x9e },
+	{ "v8dbg_type_JSObject__JS_OBJECT_TYPE", 0xa0 },
+	{ "v8dbg_type_JSRegExp__JS_REGEXP_TYPE", 0xa6 },
+	{ "v8dbg_type_JSValue__JS_VALUE_TYPE", 0x9f },
+	{ "v8dbg_type_Map__MAP_TYPE", 0x80 },
+	{ "v8dbg_type_ObjectTemplateInfo__OBJECT_TEMPLATE_INFO_TYPE", 0x95 },
+	{ "v8dbg_type_Oddball__ODDBALL_TYPE", 0x82 },
+	{ "v8dbg_type_Script__SCRIPT_TYPE", 0x98 },
+	{ "v8dbg_type_SeqAsciiString__ASCII_STRING_TYPE", 0x4 },
+	{ "v8dbg_type_SeqAsciiString__ASCII_SYMBOL_TYPE", 0x44 },
+	{ "v8dbg_type_SharedFunctionInfo__SHARED_FUNCTION_INFO_TYPE", 0x9d },
+	{ "v8dbg_type_SignatureInfo__SIGNATURE_INFO_TYPE", 0x96 },
+	{ "v8dbg_type_String__STRING_TYPE", 0x0 },
+	{ "v8dbg_type_String__SYMBOL_TYPE", 0x40 },
+	{ "v8dbg_type_TypeSwitchInfo__TYPE_SWITCH_INFO_TYPE", 0x97 },
+
+	{ "v8dbg_class_AccessCheckInfo__data__Object", 0xc },
+	{ "v8dbg_class_AccessCheckInfo__indexed_callback__Object", 0x8 },
+	{ "v8dbg_class_AccessCheckInfo__named_callback__Object", 0x4 },
+	{ "v8dbg_class_AccessorInfo__data__Object", 0xc },
+	{ "v8dbg_class_AccessorInfo__flag__Smi", 0x14 },
+	{ "v8dbg_class_AccessorInfo__getter__Object", 0x4 },
+	{ "v8dbg_class_AccessorInfo__name__Object", 0x10 },
+	{ "v8dbg_class_AccessorInfo__setter__Object", 0x8 },
+	{ "v8dbg_class_BreakPointInfo__break_point_objects__Object", 0x10 },
+	{ "v8dbg_class_BreakPointInfo__code_position__Smi", 0x4 },
+	{ "v8dbg_class_BreakPointInfo__source_position__Smi", 0x8 },
+	{ "v8dbg_class_BreakPointInfo__statement_position__Smi", 0xc },
+	{ "v8dbg_class_ByteArray__length__SMI", 0x4 },
+	{ "v8dbg_class_CallHandlerInfo__callback__Object", 0x4 },
+	{ "v8dbg_class_CallHandlerInfo__data__Object", 0x8 },
+	{ "v8dbg_class_Code__deoptimization_data__FixedArray", 0xc },
+	{ "v8dbg_class_Code__instruction_size__int", 0x4 },
+	{ "v8dbg_class_Code__instruction_start__int", 0x20 },
+	{ "v8dbg_class_Code__relocation_info__ByteArray", 0x8 },
+	{ "v8dbg_class_CodeCache__default_cache__FixedArray", 0x4 },
+	{ "v8dbg_class_CodeCache__normal_type_cache__Object", 0x8 },
+	{ "v8dbg_class_ConsString__first__String", 0xc },
+	{ "v8dbg_class_ConsString__second__String", 0x10 },
+	{ "v8dbg_class_DebugInfo__break_points__FixedArray", 0x14 },
+	{ "v8dbg_class_DebugInfo__code__Code", 0xc },
+	{ "v8dbg_class_DebugInfo__original_code__Code", 0x8 },
+	{ "v8dbg_class_DebugInfo__shared__SharedFunctionInfo", 0x4 },
+	{ "v8dbg_class_ExternalString__resource__Object", 0xc },
+	{ "v8dbg_class_FixedArray__data__uintptr_t", 0x8 },
+	{ "v8dbg_class_FixedArray__length__SMI", 0x4 },
+	{ "v8dbg_class_FunctionTemplateInfo__access_check_info__Object", 0x38 },
+	{ "v8dbg_class_FunctionTemplateInfo__call_code__Object", 0x10 },
+	{ "v8dbg_class_FunctionTemplateInfo__class_name__Object", 0x2c },
+	{ "v8dbg_class_FunctionTemplateInfo__flag__Smi", 0x3c },
+	{ "v8dbg_class_FunctionTemplateInfo__"
+		"indexed_property_handler__Object", 0x24 },
+	{ "v8dbg_class_FunctionTemplateInfo__"
+		"instance_call_handler__Object", 0x34 },
+	{ "v8dbg_class_FunctionTemplateInfo__instance_template__Object", 0x28 },
+	{ "v8dbg_class_FunctionTemplateInfo__"
+		"named_property_handler__Object", 0x20 },
+	{ "v8dbg_class_FunctionTemplateInfo__parent_template__Object", 0x1c },
+	{ "v8dbg_class_FunctionTemplateInfo__"
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+	{ "v8dbg_class_Oddball__to_number__Object", 0x8 },
+	{ "v8dbg_class_Oddball__to_string__String", 0x4 },
+	{ "v8dbg_class_PolymorphicCodeCache__cache__Object", 0x4 },
+	{ "v8dbg_class_Script__column_offset__Smi", 0x10 },
+	{ "v8dbg_class_Script__compilation_type__Smi", 0x24 },
+	{ "v8dbg_class_Script__context_data__Object", 0x18 },
+	{ "v8dbg_class_Script__data__Object", 0x14 },
+	{ "v8dbg_class_Script__eval_from_instructions_offset__Smi", 0x34 },
+	{ "v8dbg_class_Script__eval_from_shared__Object", 0x30 },
+	{ "v8dbg_class_Script__id__Object", 0x2c },
+	{ "v8dbg_class_Script__line_ends__Object", 0x28 },
+	{ "v8dbg_class_Script__line_offset__Smi", 0xc },
+	{ "v8dbg_class_Script__name__Object", 0x8 },
+	{ "v8dbg_class_Script__source__Object", 0x4 },
+	{ "v8dbg_class_Script__type__Smi", 0x20 },
+	{ "v8dbg_class_Script__wrapper__Foreign", 0x1c },
+	{ "v8dbg_class_SeqAsciiString__chars__char", 0xc },
+	{ "v8dbg_class_SharedFunctionInfo__code__Code", 0x8 },
+	{ "v8dbg_class_SharedFunctionInfo__compiler_hints__SMI", 0x50 },
+	{ "v8dbg_class_SharedFunctionInfo__construct_stub__Code", 0x10 },
+	{ "v8dbg_class_SharedFunctionInfo__debug_info__Object", 0x20 },
+	{ "v8dbg_class_SharedFunctionInfo__end_position__SMI", 0x48 },
+	{ "v8dbg_class_SharedFunctionInfo__expected_nof_properties__SMI",
+		0x3c },
+	{ "v8dbg_class_SharedFunctionInfo__formal_parameter_count__SMI", 0x38 },
+	{ "v8dbg_class_SharedFunctionInfo__function_data__Object", 0x18 },
+	{ "v8dbg_class_SharedFunctionInfo__function_token_position__SMI",
+		0x4c },
+	{ "v8dbg_class_SharedFunctionInfo__inferred_name__String", 0x24 },
+	{ "v8dbg_class_SharedFunctionInfo__initial_map__Object", 0x28 },
+	{ "v8dbg_class_SharedFunctionInfo__instance_class_name__Object", 0x14 },
+	{ "v8dbg_class_SharedFunctionInfo__length__SMI", 0x34 },
+	{ "v8dbg_class_SharedFunctionInfo__name__Object", 0x4 },
+	{ "v8dbg_class_SharedFunctionInfo__num_literals__SMI", 0x40 },
+	{ "v8dbg_class_SharedFunctionInfo__opt_count__SMI", 0x58 },
+	{ "v8dbg_class_SharedFunctionInfo__script__Object", 0x1c },
+	{ "v8dbg_class_SharedFunctionInfo__"
+		"start_position_and_type__SMI", 0x44 },
+	{ "v8dbg_class_SharedFunctionInfo__"
+		"this_property_assignments__Object", 0x2c },
+	{ "v8dbg_class_SharedFunctionInfo__"
+		"this_property_assignments_count__SMI", 0x54 },
+	{ "v8dbg_class_SignatureInfo__args__Object", 0x8 },
+	{ "v8dbg_class_SignatureInfo__receiver__Object", 0x4 },
+	{ "v8dbg_class_SlicedString__offset__SMI", 0x10 },
+	{ "v8dbg_class_String__length__SMI", 0x4 },
+	{ "v8dbg_class_TemplateInfo__property_list__Object", 0x8 },
+	{ "v8dbg_class_TemplateInfo__tag__Object", 0x4 },
+	{ "v8dbg_class_TypeSwitchInfo__types__Object", 0x4 },
+
+	{ "v8dbg_parent_AccessCheckInfo__Struct", 0x0 },
+	{ "v8dbg_parent_AccessorInfo__Struct", 0x0 },
+	{ "v8dbg_parent_BreakPointInfo__Struct", 0x0 },
+	{ "v8dbg_parent_ByteArray__FixedArrayBase", 0x0 },
+	{ "v8dbg_parent_CallHandlerInfo__Struct", 0x0 },
+	{ "v8dbg_parent_Code__HeapObject", 0x0 },
+	{ "v8dbg_parent_CodeCache__Struct", 0x0 },
+	{ "v8dbg_parent_ConsString__String", 0x0 },
+	{ "v8dbg_parent_DebugInfo__Struct", 0x0 },
+	{ "v8dbg_parent_DeoptimizationInputData__FixedArray", 0x0 },
+	{ "v8dbg_parent_DeoptimizationOutputData__FixedArray", 0x0 },
+	{ "v8dbg_parent_DescriptorArray__FixedArray", 0x0 },
+	{ "v8dbg_parent_ExternalArray__FixedArrayBase", 0x0 },
+	{ "v8dbg_parent_ExternalAsciiString__ExternalString", 0x0 },
+	{ "v8dbg_parent_ExternalByteArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalDoubleArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalFloatArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalIntArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalPixelArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalShortArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalString__String", 0x0 },
+	{ "v8dbg_parent_ExternalTwoByteString__ExternalString", 0x0 },
+	{ "v8dbg_parent_ExternalUnsignedByteArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalUnsignedIntArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_ExternalUnsignedShortArray__ExternalArray", 0x0 },
+	{ "v8dbg_parent_Failure__MaybeObject", 0x0 },
+	{ "v8dbg_parent_FixedArray__FixedArrayBase", 0x0 },
+	{ "v8dbg_parent_FixedArrayBase__HeapObject", 0x0 },
+	{ "v8dbg_parent_FixedDoubleArray__FixedArrayBase", 0x0 },
+	{ "v8dbg_parent_Foreign__HeapObject", 0x0 },
+	{ "v8dbg_parent_FunctionTemplateInfo__TemplateInfo", 0x0 },
+	{ "v8dbg_parent_GlobalObject__JSObject", 0x0 },
+	{ "v8dbg_parent_HashTable__FixedArray", 0x0 },
+	{ "v8dbg_parent_HeapNumber__HeapObject", 0x0 },
+	{ "v8dbg_parent_HeapObject__Object", 0x0 },
+	{ "v8dbg_parent_InterceptorInfo__Struct", 0x0 },
+	{ "v8dbg_parent_JSArray__JSObject", 0x0 },
+	{ "v8dbg_parent_JSBuiltinsObject__GlobalObject", 0x0 },
+	{ "v8dbg_parent_JSFunction__JSObject", 0x0 },
+	{ "v8dbg_parent_JSFunctionProxy__JSProxy", 0x0 },
+	{ "v8dbg_parent_JSFunctionResultCache__FixedArray", 0x0 },
+	{ "v8dbg_parent_JSGlobalObject__GlobalObject", 0x0 },
+	{ "v8dbg_parent_JSGlobalPropertyCell__HeapObject", 0x0 },
+	{ "v8dbg_parent_JSMessageObject__JSObject", 0x0 },
+	{ "v8dbg_parent_JSObject__JSReceiver", 0x0 },
+	{ "v8dbg_parent_JSProxy__JSReceiver", 0x0 },
+	{ "v8dbg_parent_JSReceiver__HeapObject", 0x0 },
+	{ "v8dbg_parent_JSRegExp__JSObject", 0x0 },
+	{ "v8dbg_parent_JSRegExpResult__JSArray", 0x0 },
+	{ "v8dbg_parent_JSValue__JSObject", 0x0 },
+	{ "v8dbg_parent_JSWeakMap__JSObject", 0x0 },
+	{ "v8dbg_parent_Map__HeapObject", 0x0 },
+	{ "v8dbg_parent_NormalizedMapCache__FixedArray", 0x0 },
+	{ "v8dbg_parent_ObjectTemplateInfo__TemplateInfo", 0x0 },
+	{ "v8dbg_parent_Oddball__HeapObject", 0x0 },
+	{ "v8dbg_parent_PolymorphicCodeCache__Struct", 0x0 },
+	{ "v8dbg_parent_Script__Struct", 0x0 },
+	{ "v8dbg_parent_SeqAsciiString__SeqString", 0x0 },
+	{ "v8dbg_parent_SeqString__String", 0x0 },
+	{ "v8dbg_parent_SeqTwoByteString__SeqString", 0x0 },
+	{ "v8dbg_parent_SharedFunctionInfo__HeapObject", 0x0 },
+	{ "v8dbg_parent_SignatureInfo__Struct", 0x0 },
+	{ "v8dbg_parent_SlicedString__String", 0x0 },
+	{ "v8dbg_parent_Smi__Object", 0x0 },
+	{ "v8dbg_parent_String__HeapObject", 0x0 },
+	{ "v8dbg_parent_Struct__HeapObject", 0x0 },
+	{ "v8dbg_parent_TemplateInfo__Struct", 0x0 },
+	{ "v8dbg_parent_TypeSwitchInfo__Struct", 0x0 },
+
+	{ "v8dbg_frametype_ArgumentsAdaptorFrame", 0x8 },
+	{ "v8dbg_frametype_ConstructFrame", 0x7 },
+	{ "v8dbg_frametype_EntryConstructFrame", 0x2 },
+	{ "v8dbg_frametype_EntryFrame", 0x1 },
+	{ "v8dbg_frametype_ExitFrame", 0x3 },
+	{ "v8dbg_frametype_InternalFrame", 0x6 },
+	{ "v8dbg_frametype_JavaScriptFrame", 0x4 },
+	{ "v8dbg_frametype_OptimizedFrame", 0x5 },
+
+	{ "v8dbg_off_fp_args", 0x8 },
+	{ "v8dbg_off_fp_context", -0x4 },
+	{ "v8dbg_off_fp_function", -0x8 },
+	{ "v8dbg_off_fp_marker", -0x8 },
+
+	{ "v8dbg_prop_idx_content", 0x1 },
+	{ "v8dbg_prop_idx_first", 0x3 },
+	{ "v8dbg_prop_type_field", 0x1 },
+	{ "v8dbg_prop_type_first_phantom", 0x6 },
+	{ "v8dbg_prop_type_mask", 0xf },
+
+	{ "v8dbg_AsciiStringTag", 0x4 },
+	{ "v8dbg_PointerSizeLog2", 0x2 },
+	{ "v8dbg_SeqStringTag", 0x0 },
+	{ "v8dbg_SmiTag", 0x0 },
+	{ "v8dbg_SmiTagMask", 0x1 },
+	{ "v8dbg_SmiValueShift", 0x1 },
+	{ "v8dbg_StringEncodingMask", 0x4 },
+	{ "v8dbg_StringRepresentationMask", 0x3 },
+	{ "v8dbg_StringTag", 0x0 },
+	{ "v8dbg_TwoByteStringTag", 0x0 },
+	{ "v8dbg_ConsStringTag", 0x1 },
+	{ "v8dbg_ExternalStringTag", 0x2 },
+	{ "v8dbg_FailureTag", 0x3 },
+	{ "v8dbg_FailureTagMask", 0x3 },
+	{ "v8dbg_FirstNonstringType", 0x80 },
+	{ "v8dbg_HeapObjectTag", 0x1 },
+	{ "v8dbg_HeapObjectTagMask", 0x3 },
+	{ "v8dbg_IsNotStringMask", 0x80 },
+	{ "v8dbg_NotStringTag", 0x80 },
+
+	{ NULL },
+};
+
+v8_cfg_t v8_cfg_04 = { "node-0.4", "node v0.4", v8_symbols_node_04,
+    v8cfg_canned_iter, v8cfg_canned_readsym };
+
+v8_cfg_t v8_cfg_06 = { "node-0.6", "node v0.6", v8_symbols_node_06,
+    v8cfg_canned_iter, v8cfg_canned_readsym };
+
+v8_cfg_t *v8_cfgs[] = {
+	&v8_cfg_04,
+	&v8_cfg_06,
+	NULL
+};
+
+v8_cfg_t v8_cfg_target = { NULL, NULL, NULL, v8cfg_target_iter,
+	v8cfg_target_readsym };
diff --git a/deps/mdb_v8/v8cfg.h b/deps/mdb_v8/v8cfg.h
new file mode 100644
index 000000000..8c5231e42
--- /dev/null
+++ b/deps/mdb_v8/v8cfg.h
@@ -0,0 +1,52 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * v8cfg.h: canned configurations for previous V8 versions
+ */
+
+#ifndef V8CFG_H
+#define	V8CFG_H
+
+#include <sys/types.h>
+#include <sys/mdb_modapi.h>
+
+typedef struct {
+	const char 	*v8cs_name;	/* symbol name */
+	intptr_t	v8cs_value;	/* symbol value */
+} v8_cfg_symbol_t;
+
+typedef struct v8_cfg {
+	const char 	*v8cfg_name;	/* canned config name */
+	const char 	*v8cfg_label;	/* description */
+	v8_cfg_symbol_t	*v8cfg_symbols;	/* actual symbol values */
+
+	int (*v8cfg_iter)(struct v8_cfg *, int (*)(mdb_symbol_t *, void *),
+	    void *);
+	int (*v8cfg_readsym)(struct v8_cfg *, const char *, intptr_t *);
+} v8_cfg_t;
+
+extern v8_cfg_t v8_cfg_04;
+extern v8_cfg_t v8_cfg_06;
+extern v8_cfg_t v8_cfg_target;
+extern v8_cfg_t *v8_cfgs[];
+
+#endif /* V8CFG_H */
diff --git a/deps/mdb_v8/v8dbg.h b/deps/mdb_v8/v8dbg.h
new file mode 100644
index 000000000..6e56e979c
--- /dev/null
+++ b/deps/mdb_v8/v8dbg.h
@@ -0,0 +1,78 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * v8dbg.h: macros for use by V8 heap inspection tools.  The consumer must
+ * define values for various tags and shifts.  The MDB module gets these
+ * constants from information encoded in the binary itself.
+ */
+
+#ifndef _V8DBG_H
+#define	_V8DBG_H
+
+/*
+ * Recall that while V8 heap objects are always 4-byte aligned, heap object
+ * pointers always have the last bit set.  So when looking for a field nominally
+ * at offset X, one must be sure to clear the tag bit first.
+ */
+#define	V8_OFF_HEAP(x)			((x) - V8_HeapObjectTag)
+
+/*
+ * Determine whether a given pointer refers to a SMI, Failure, or HeapObject.
+ */
+#define	V8_IS_SMI(ptr)		(((ptr) & V8_SmiTagMask) == V8_SmiTag)
+#define	V8_IS_FAILURE(ptr)	(((ptr) & V8_FailureTagMask) == V8_FailureTag)
+#define	V8_IS_HEAPOBJECT(ptr)	\
+	(((ptr) & V8_HeapObjectTagMask) == V8_HeapObjectTag)
+
+/*
+ * Extract the value of a SMI "pointer".  Recall that small integers are stored
+ * using the upper 31 bits.
+ */
+#define	V8_SMI_VALUE(smi)	((smi) >> (V8_SmiValueShift + V8_SmiShiftSize))
+
+/*
+ * Determine the encoding and representation of a V8 string.
+ */
+#define	V8_TYPE_STRING(type)	(((type) & V8_IsNotStringMask) == V8_StringTag)
+
+#define	V8_STRENC_ASCII(type)	\
+	(((type) & V8_StringEncodingMask) == V8_AsciiStringTag)
+
+#define	V8_STRREP_SEQ(type)	\
+	(((type) & V8_StringRepresentationMask) == V8_SeqStringTag)
+#define	V8_STRREP_CONS(type)	\
+	(((type) & V8_StringRepresentationMask) == V8_ConsStringTag)
+#define	V8_STRREP_EXT(type)	\
+	(((type) & V8_StringRepresentationMask) == V8_ExternalStringTag)
+
+/*
+ * Several of the following constants and transformations are hardcoded in V8 as
+ * well, so there's no way to extract them programmatically from the binary.
+ */
+#define	V8_DESC_KEYIDX(x)		((x) + V8_PROP_IDX_FIRST)
+#define	V8_DESC_VALIDX(x)		((x) << 1)
+#define	V8_DESC_DETIDX(x)		(((x) << 1) + 1)
+
+#define	V8_DESC_ISFIELD(x)		\
+	((V8_SMI_VALUE(x) & V8_PROP_TYPE_MASK) == V8_PROP_TYPE_FIELD)
+
+#endif /* _V8DBG_H */
diff --git a/node.gyp b/node.gyp
index d1d7df176..c289ce881 100644
--- a/node.gyp
+++ b/node.gyp
@@ -16,6 +16,7 @@
     'node_use_openssl%': 'true',
     'node_use_systemtap%': 'false',
     'node_shared_openssl%': 'false',
+    'node_use_mdb%': 'false',
     'library_files': [
       'src/node.js',
       'lib/_debugger.js',
@@ -205,6 +206,13 @@
             }
           ] ]
         } ],
+        [ 'node_use_mdb=="true"', {
+          'dependencies': [ 'node_mdb' ],
+          'include_dirs': [ '<(SHARED_INTERMEDIATE_DIR)' ],
+          'sources': [
+            'src/node_mdb.cc',
+          ],
+        } ],
         [ 'node_use_systemtap=="true"', {
           'defines': [ 'HAVE_SYSTEMTAP=1', 'STAP_SDT_V1=1' ],
           'sources': [
@@ -409,6 +417,32 @@
       ]
     },
     {
+      'target_name': 'node_mdb',
+      'type': 'none',
+      'conditions': [
+        [ 'node_use_mdb=="true"',
+          {
+            'dependencies': [ 'deps/mdb_v8/mdb_v8.gyp:mdb_v8' ],
+            'actions': [
+              {
+                'action_name': 'node_mdb',
+                'inputs': [ '<(PRODUCT_DIR)/obj.target/deps/mdb_v8/mdb_v8.so' ],
+                'outputs': [ '<(PRODUCT_DIR)/obj.target/node/src/node_mdb.o' ],
+                'conditions': [
+                  [ 'target_arch=="ia32"', {
+                    'action': [ 'elfwrap', '-32', '-o', '<@(_outputs)', '<@(_inputs)' ],
+                  } ],
+                  [ 'target_arch=="x64"', {
+                    'action': [ 'elfwrap', '-64', '-o', '<@(_outputs)', '<@(_inputs)' ],
+                  } ],
+                ],
+              },
+            ],
+          },
+        ],
+      ],
+    },
+    {
       'target_name': 'node_dtrace_provider',
       'type': 'none',
       'conditions': [
diff --git a/tools/mdb/extract_dmod.c b/tools/mdb/extract_dmod.c
new file mode 100644
index 000000000..0efc94a8f
--- /dev/null
+++ b/tools/mdb/extract_dmod.c
@@ -0,0 +1,97 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * gcc -Wall -lproc -o extract_dmod extract_dmod.c
+ *
+ * use this tool to extract the mdb_v8.so from a core file for use with older
+ * mdb or platforms with an out of date v8.so
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <strings.h>
+#include <errno.h>
+#include <libproc.h>
+#include <sys/sysmacros.h>
+
+const char *g_sym = "mdb_v8.so_start";
+
+int
+main(int argc, const char *argv[])
+{
+	int ifd, ofd, perr, toread, ret;
+	struct ps_prochandle *p;
+	GElf_Sym sym;
+	prsyminfo_t si;
+	char buf[1024];
+
+	if (argc != 3) {
+		fprintf(stderr, "pdump: <infile> <outfile>\n");
+		return (1);
+	}
+
+	ifd = open(argv[1], O_RDONLY);
+	if (ifd < 0) {
+		fprintf(stderr, "failed to open: %s: %s\n",
+		    argv[1], strerror(errno));
+		return (1);
+	}
+	ofd = open(argv[2], O_RDWR | O_CREAT | O_TRUNC);
+	if (ofd < 0) {
+		fprintf(stderr, "failed to open: %s: %s\n",
+		    argv[1], strerror(errno));
+		return (1);
+	}
+
+	p = Pfgrab_core(ifd, NULL, &perr); 
+	if (p == NULL) {
+		fprintf(stderr, "failed to grab core file\n");
+		return (1);
+	}
+
+	if (Pxlookup_by_name(p, NULL, "a.out", g_sym, &sym, &si) != 0) {
+		fprintf(stderr, "failed to lookup symobl %s\n", g_sym);
+		return (0);
+	}
+
+	while (sym.st_size > 0) {
+		toread = MIN(sym.st_size, sizeof (buf));
+		ret = Pread(p, buf, toread, sym.st_value);
+		if (ret < 0) {
+			fprintf(stderr, "failed to Pread...\n");
+			return (1);
+		}
+		if (ret != 0)
+			ret = write(ofd, buf, ret);
+		if (ret < 0) {
+			fprintf(stderr, "failed to write to output file %s\n",
+			    strerror(errno));
+		}
+		sym.st_size -= ret;
+		sym.st_value += ret;
+	}
+
+	return (0);
+}