diff --git a/Cargo.toml b/Cargo.toml
index 9df16bf..271583c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,3 +10,5 @@ default-members = [
     "decode",
     "messages",
 ]
+
+resolver = "2"
diff --git a/dtrace/trace-messages.d b/dtrace/trace-messages.d
old mode 100644
new mode 100755
index 95a8fd5..cb9cd89
--- a/dtrace/trace-messages.d
+++ b/dtrace/trace-messages.d
@@ -2,22 +2,21 @@
 
 xcvr-ctl$target:::message-sent
 {
-	peer = json(copyinstr(arg0), "ok");
-	msg = json(copyinstr(arg1), "ok");
-    vers = json(msg, "version");
-    body = json(msg, "body");
+    peer = json(copyinstr(arg0), "ok");
+    header = json(copyinstr(arg1), "ok");
+    msg = json(copyinstr(arg2), "ok");
     printf("Sent message to %s\n", peer);
-    printf("  version: %s\n", vers);
-    printf("  body: %s\n", body);
+    printf("  header: %s\n", header);
+    printf("  msg: %s\n", msg);
 }
 
 xcvr-ctl$target:::message-received
 {
-	peer = json(copyinstr(arg0), "ok");
-	msg = json(copyinstr(arg1), "ok");
-    vers = json(msg, "version");
+    peer = json(copyinstr(arg0), "ok");
+    header = json(copyinstr(arg1), "ok");
+    msg = json(copyinstr(arg2), "ok");
     body = json(msg, "body");
     printf("Recv message from %s\n", peer);
-    printf("  version: %s\n", vers);
-    printf("  body: %s\n", body);
+    printf("  header: %s\n", header);
+    printf("  msg: %s\n", msg);
 }
diff --git a/dtrace/trace-packets.d b/dtrace/trace-packets.d
old mode 100644
new mode 100755
index 8cf5273..d8b251c
--- a/dtrace/trace-packets.d
+++ b/dtrace/trace-packets.d
@@ -1,5 +1,7 @@
 #!/usr/sbin/dtrace -CZqs
 
+#pragma D option bufsize=16k
+
 /*
  * Constants used to pick out parts of SP responses.
  *
@@ -13,90 +15,159 @@
  * - 1 u64 for the message ID
  * - 1 u8 for the message kind variant ID
  *
- * For 10 bytes total.
+ * For 10 octets total.
  *
  * Message has:
  *
  * - 1 u8 for the version
  * - 1 u8 for the MessageBody variant ID
  *
- * For 2 bytes total
+ * For 2 octets total
  *
- * For an SpResponse::Status:
+ * For the MessageBody::SpResponse, which we support printing on receipt, the
+ * contents are:
  *
- * - 1 u8 for the variant ID
+ * - 1 u8 for the variant ID (e.g., SpResponse::Read)
  * - 2 u64s for the successful and failed module IDs.
  *
- * For 17 bytes total.
- *
- * So the data should start at:
- *
- * 10 + 2 + 17 = 29 octets into the message.
+ * For 17 octets total.
  */
-#define HEADER_VERSION_OFFSET 0
+#define HEADER_VERSION_OFFSET (0)
 #define HEADER_MESSAGE_ID_OFFSET (1)
-#define HEADER_MESSAGE_KIND_OFFSET (9)
+#define HEADER_MESSAGE_KIND_OFFSET (HEADER_MESSAGE_ID_OFFSET + 8)
 #define MESSAGE_VERSION_OFFSET (HEADER_MESSAGE_KIND_OFFSET + 1)
 #define MESSAGE_BODY_VARIANT_OFFSET (MESSAGE_VERSION_OFFSET + 1)
 #define SP_RESPONSE_VARIANT_OFFSET (MESSAGE_BODY_VARIANT_OFFSET + 1)
-#define MODULE_ID_OFFSET (SP_RESPONSE_VARIANT_OFFSET + 1)
-#define STATUS_DATA_OFFSET (MODULE_ID_OFFSET + 16)
+#define SUCCESS_MODULE_ID_OFFSET (SP_RESPONSE_VARIANT_OFFSET + 1)
+#define FAILED_MODULE_ID_OFFSET (SUCCESS_MODULE_ID_OFFSET + 8)
+
+/*
+ * Definitions of the `MessageKind` enum
+ */
+#define MESSAGE_KIND_ERROR (0)
+#define MESSAGE_KIND_HOST_REQUEST (1)
+#define MESSAGE_KIND_SP_RESPONSE (2)
 
-#define MESSAGE_KIND_SP_RESPONSE 2
-#define SP_RESPONSE_STATUS 2
-#define SP_RESPONSE_EXTENDED_STATUS 6
-#define SP_RESPONSE_ACK 3
+/*
+ * Definitions of the `SpResponse` enum discriminant.
+ */
+#define SP_RESPONSE_READ (0)
+#define SP_RESPONSE_WRITE (1)
+#define SP_RESPONSE_STATUS (2)
+#define SP_RESPONSE_ACK (3)
+#define SP_RESPONSE_EXTENDED_STATUS (6)
 
 xcvr-ctl$target:::packet-sent
 {
-	peer = json(copyinstr(arg0), "ok");
-	n_bytes = arg1;
-	buf = (char*)copyin(arg2, n_bytes);
-	vers = *(uint8_t*) buf;
-	message_id = *(uint64_t*) (buf + HEADER_MESSAGE_ID_OFFSET);
-	message_kind = *(uint8_t*) (buf + HEADER_MESSAGE_KIND_OFFSET);
-
-	printf("Sent payload to %s\n", peer);
-	printf("  n_bytes: %d\n", n_bytes);
-	printf("  version: %d\n", vers);
-	printf("  msg id: %d\n", message_id);
-	printf("  msg kind: %d\n", message_kind);
+    this->peer = json(copyinstr(arg0), "ok");
+    this->n_bytes = arg1;
+    this->buf = (char*)copyin(arg2, this->n_bytes);
+    this->vers = *(uint8_t*) this->buf;
+    this->message_id = *(uint64_t*) (this->buf + HEADER_MESSAGE_ID_OFFSET);
+    this->message_kind = *(uint8_t*) (this->buf + HEADER_MESSAGE_KIND_OFFSET);
+
+    printf("Sent payload to %s\n", this->peer);
+    printf("  n_bytes: %d\n", this->n_bytes);
+    printf("  version: %d\n", this->vers);
+    printf("  msg id: %d\n", this->message_id);
+
+    this->message_kind_str = "Unknown";
+    if (this->message_kind == MESSAGE_KIND_ERROR) {
+        this->message_kind_str = "Error";
+    } else if (this->message_kind == MESSAGE_KIND_HOST_REQUEST) {
+        this->message_kind_str = "HostRequest";
+    } else if (this->message_kind == MESSAGE_KIND_SP_RESPONSE) {
+        this->message_kind_str = "SpResponse";
+    }
+    printf("  msg kind: %s (%d)\n", this->message_kind_str, this->message_kind);
+}
+
+/* "First" action on receiving a packet. Copy in the main metadata. */
+xcvr-ctl$target:::packet-received
+{
+    this->peer = json(copyinstr(arg0), "ok");
+    this->n_bytes = arg1;
+
+    /* Pointer to the packet payload itself. */
+    this->buf = (char*) copyin(arg2, this->n_bytes);
+    this->vers = this->buf[0];
+    this->message_id = *(uint64_t*) (this->buf + HEADER_MESSAGE_ID_OFFSET);
+    this->message_kind = this->buf[HEADER_MESSAGE_KIND_OFFSET];
+    printf("Recv payload from: %s\n", this->peer);
+    printf("  Raw packet:\n");
+    tracemem(this->buf, 128, this->n_bytes);
+    printf("  n_bytes: %d\n", this->n_bytes);
+    printf("  version: %d\n", this->vers);
+    printf("  msg id: %d\n", this->message_id);
+}
+
+/* Print the MessageKinds */
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_ERROR/
+{
+    printf("  msg kind: Error (%d)\n", this->message_kind);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_HOST_REQUEST/
+{
+    printf("  msg kind: HostRequest (%d)\n", this->message_kind);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE/
+{
+    printf("  msg kind: SpResponse (%d)\n", this->message_kind);
+    this->message_body_variant = this->buf[MESSAGE_BODY_VARIANT_OFFSET];
+}
+
+/* Print the SP response kind, note these are printed in order. */
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE &&
+this->message_body_variant == SP_RESPONSE_STATUS/
+{
+    printf("MessageBody: Status (%d)\n", this->message_body_variant);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE &&
+this->message_body_variant == SP_RESPONSE_READ/
+{
+    printf("MessageBody: Read (%d)\n", this->message_body_variant);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE &&
+this->message_body_variant == SP_RESPONSE_WRITE/
+{
+    printf("MessageBody: Write (%d)\n", this->message_body_variant);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE &&
+this->message_body_variant == SP_RESPONSE_ACK/
+{
+    printf("MessageBody: Ack (%d)\n", this->message_body_variant);
+}
+
+xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE &&
+this->message_body_variant == SP_RESPONSE_EXTENDED_STATUS/
+{
+    printf("MessageBody: ExtendedStatus (%d)\n", this->message_body_variant);
 }
 
+/* Then print the module IDs and remaining data. */
 xcvr-ctl$target:::packet-received
+/this->message_kind == MESSAGE_KIND_SP_RESPONSE/
 {
-	peer = json(copyinstr(arg0), "ok");
-	n_bytes = arg1;
-
-	/* Pointer to the packet payload itself. */
-	buf = (char*) copyin(arg2, n_bytes);
-
-	vers = buf[0];
-	message_id = *(uint64_t*) (buf + HEADER_MESSAGE_ID_OFFSET);
-	message_kind = buf[HEADER_MESSAGE_KIND_OFFSET];
-
-	printf("Recv payload from: %s\n", peer);
-	printf("  n_bytes: %d\n", n_bytes);
-	printf("  version: %d\n", vers);
-	printf("  msg id: %d\n", message_id);
-	printf("  msg kind: %d\n", message_kind);
-
-	/* Print SpResponse data, for certain kinds of messages */
-	if (message_kind == MESSAGE_KIND_SP_RESPONSE) {
-		message_body_variant = buf[MESSAGE_BODY_VARIANT_OFFSET];
-		if (message_body_variant == MESSAGE_KIND_SP_RESPONSE) {
-			sp_response_variant = buf[SP_RESPONSE_VARIANT_OFFSET];
-			if ((sp_response_variant == SP_RESPONSE_STATUS) ||
-				(sp_response_variant == SP_RESPONSE_EXTENDED_STATUS) ||
-				(sp_response_variant == SP_RESPONSE_ACK))
-			{
-				printf("  module IDs:\n");
-				tracemem(buf + MODULE_ID_OFFSET, 16);
-				n_octets = n_bytes - STATUS_DATA_OFFSET;
-				data = (buf + STATUS_DATA_OFFSET);
-				printf("  data (up to %d octets): ", n_octets);
-				tracemem(data, 128, n_octets);
-			}
-		}
-	}
+    this->success_modules = *(uint64_t*)(this->buf + SUCCESS_MODULE_ID_OFFSET);
+    this->failed_modules = *(uint64_t*)(this->buf + FAILED_MODULE_ID_OFFSET);
+    printf("  successful module IDs: 0x%08x\n", this->success_modules);
+    printf("  failed module IDs:     0x%08x\n", this->failed_modules);
+    this->n_octets = this->n_bytes - FAILED_MODULE_ID_OFFSET;
+    this->data = (this->buf + FAILED_MODULE_ID_OFFSET);
+    printf("  remaining data (up to %d octets):\n", this->n_octets);
+    tracemem(this->data, 128, this->n_octets);
+    printf("\n");
 }