diff --git a/lib/libnvmf/nvmf_host.c b/lib/libnvmf/nvmf_host.c
--- a/lib/libnvmf/nvmf_host.c
+++ b/lib/libnvmf/nvmf_host.c
@@ -498,7 +498,7 @@
 	nvmf_init_sqe(&cmd, NVME_OPC_IDENTIFY);
 
 	/* 5.15.1 Use CNS of 0x01 for controller data. */
-	cmd.cdw10 = htole32(1);
+	cmd.cdw10 = htole32(NVME_CNS_ID_CONTROLLER);
 
 	cc = nvmf_allocate_command(qp, &cmd);
 	if (cc == NULL)
@@ -547,7 +547,7 @@
 	nvmf_init_sqe(&cmd, NVME_OPC_IDENTIFY);
 
 	/* 5.15.1 Use CNS of 0x00 for namespace data. */
-	cmd.cdw10 = htole32(0);
+	cmd.cdw10 = htole32(NVME_CNS_ID_NAMESPACE);
 	cmd.nsid = htole32(nsid);
 
 	cc = nvmf_allocate_command(qp, &cmd);
diff --git a/sbin/nvmecontrol/ns.c b/sbin/nvmecontrol/ns.c
--- a/sbin/nvmecontrol/ns.c
+++ b/sbin/nvmecontrol/ns.c
@@ -422,7 +422,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(0);
-	pt.cmd.cdw10 = htole32(0x02);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ACTIVE_NAMESPACE_ID_LIST);
 	pt.buf = list;
 	pt.len = sizeof(list);
 	pt.is_read = 1;
@@ -467,7 +467,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(0);
-	pt.cmd.cdw10 = htole32(0x10);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ALLOCATED_NAMESPACE_ID_LIST);
 	pt.buf = list;
 	pt.len = sizeof(list);
 	pt.is_read = 1;
@@ -511,7 +511,7 @@
 
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
-	pt.cmd.cdw10 = htole32(0x13);
+	pt.cmd.cdw10 = htole32(NVME_CNS_CONTROLLER_LIST);
 	pt.buf = clist;
 	pt.len = sizeof(clist);
 	pt.is_read = 1;
@@ -728,7 +728,7 @@
 		/* Get full list of controllers to attach to. */
 		memset(&pt, 0, sizeof(pt));
 		pt.cmd.opc = NVME_OPC_IDENTIFY;
-		pt.cmd.cdw10 = htole32(0x13);
+		pt.cmd.cdw10 = htole32(NVME_CNS_CONTROLLER_LIST);
 		pt.buf = clist;
 		pt.len = sizeof(clist);
 		pt.is_read = 1;
@@ -799,7 +799,7 @@
 		memset(&pt, 0, sizeof(pt));
 		pt.cmd.opc = NVME_OPC_IDENTIFY;
 		pt.cmd.nsid = htole32(nsid);
-		pt.cmd.cdw10 = htole32(0x12);
+		pt.cmd.cdw10 = htole32(NVME_CNS_CONTROLLER_LIST_ATTACHED);
 		pt.buf = clist;
 		pt.len = sizeof(clist);
 		pt.is_read = 1;
@@ -874,7 +874,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(nsid);
-	pt.cmd.cdw10 = htole32(0x12);
+	pt.cmd.cdw10 = htole32(NVME_CNS_CONTROLLER_LIST_ATTACHED);
 	pt.buf = clist;
 	pt.len = sizeof(clist);
 	pt.is_read = 1;
@@ -927,7 +927,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(nsid);
-	pt.cmd.cdw10 = htole32(0x11);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ID_ALLOCATED_NAMESPACE);
 	pt.buf = &nsdata;
 	pt.len = sizeof(nsdata);
 	pt.is_read = 1;
diff --git a/sbin/nvmecontrol/nvmecontrol.c b/sbin/nvmecontrol/nvmecontrol.c
--- a/sbin/nvmecontrol/nvmecontrol.c
+++ b/sbin/nvmecontrol/nvmecontrol.c
@@ -102,7 +102,7 @@
 
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
-	pt.cmd.cdw10 = htole32(1);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ID_CONTROLLER);
 	pt.buf = cdata;
 	pt.len = sizeof(*cdata);
 	pt.is_read = 1;
@@ -126,7 +126,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(nsid);
-	pt.cmd.cdw10 = htole32(0);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ID_NAMESPACE);
 	pt.buf = nsdata;
 	pt.len = sizeof(*nsdata);
 	pt.is_read = 1;
@@ -150,7 +150,7 @@
 	memset(&pt, 0, sizeof(pt));
 	pt.cmd.opc = NVME_OPC_IDENTIFY;
 	pt.cmd.nsid = htole32(nsid);
-	pt.cmd.cdw10 = htole32(2);
+	pt.cmd.cdw10 = htole32(NVME_CNS_ACTIVE_NAMESPACE_ID_LIST);
 	pt.buf = nslist;
 	pt.len = sizeof(*nslist);
 	pt.is_read = 1;
diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -10778,7 +10778,7 @@
 	if (lun == NULL) {
 		cns = le32toh(ctnio->cmd.cdw10) & 0xff;
 		switch (cns) {
-		case 0:
+		case NVME_CNS_ID_NAMESPACE:
 			memset(ctnio->kern_data_ptr, 0, len);
 			ctl_datamove((union ctl_io *)ctnio);
 			break;
diff --git a/sys/cam/ctl/ctl_backend_block.c b/sys/cam/ctl/ctl_backend_block.c
--- a/sys/cam/ctl/ctl_backend_block.c
+++ b/sys/cam/ctl/ctl_backend_block.c
@@ -1771,10 +1771,10 @@
 
 	cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
 	switch (cns) {
-	case 0:
+	case NVME_CNS_ID_NAMESPACE:
 		ctl_be_block_namespace_data(be_lun, io);
 		break;
-	case 3:
+	case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST:
 		ctl_be_block_nvme_ids(be_lun, io);
 		break;
 	default:
@@ -3213,8 +3213,8 @@
 
 		cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
 		switch (cns) {
-		case 0:
-		case 3:
+		case NVME_CNS_ID_NAMESPACE:
+		case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST:
 			mtx_lock(&be_lun->queue_lock);
 			STAILQ_INSERT_TAIL(&be_lun->config_read_queue,
 			    &io->io_hdr, links);
diff --git a/sys/cam/ctl/ctl_backend_ramdisk.c b/sys/cam/ctl/ctl_backend_ramdisk.c
--- a/sys/cam/ctl/ctl_backend_ramdisk.c
+++ b/sys/cam/ctl/ctl_backend_ramdisk.c
@@ -658,9 +658,9 @@
 
 		cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
 		switch (cns) {
-		case 0:
+		case NVME_CNS_ID_NAMESPACE:
 			return (ramdisk_namespace_data(io));
-		case 3:
+		case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST:
 			return (ramdisk_nvme_ids(io));
 		default:
 			ctl_nvme_set_invalid_field(&io->nvmeio);
diff --git a/sys/cam/nvme/nvme_xpt.c b/sys/cam/nvme/nvme_xpt.c
--- a/sys/cam/nvme/nvme_xpt.c
+++ b/sys/cam/nvme/nvme_xpt.c
@@ -281,7 +281,7 @@
 		    sizeof(softc->cd),		/* dxfer_len */
 		    30 * 1000); /* timeout 30s */
 		nvme_ns_cmd(nvmeio, NVME_OPC_IDENTIFY, 0,
-		    1, 0, 0, 0, 0, 0);
+		    NVME_CNS_ID_CONTROLLER, 0, 0, 0, 0, 0);
 		break;
 	case NVME_PROBE_IDENTIFY_NS:
 		cam_fill_nvmeadmin(nvmeio,
@@ -292,7 +292,7 @@
 		    sizeof(softc->ns),		/* dxfer_len */
 		    30 * 1000); /* timeout 30s */
 		nvme_ns_cmd(nvmeio, NVME_OPC_IDENTIFY, lun,
-		    0, 0, 0, 0, 0, 0);
+		    NVME_CNS_ID_NAMESPACE, 0, 0, 0, 0, 0);
 		break;
 	default:
 		panic("nvme_probe_start: invalid action state 0x%x\n", softc->action);
diff --git a/sys/dev/nvme/nvme.h b/sys/dev/nvme/nvme.h
--- a/sys/dev/nvme/nvme.h
+++ b/sys/dev/nvme/nvme.h
@@ -1142,6 +1142,20 @@
 
 _Static_assert(sizeof(struct nvme_power_state) == 32, "bad size for nvme_power_state");
 
+#define NVME_CNS_ID_NAMESPACE			0x00
+#define NVME_CNS_ID_CONTROLLER			0x01
+#define NVME_CNS_ACTIVE_NAMESPACE_ID_LIST	0x02
+#define NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST	0x03
+#define NVME_CNS_NVM_SET_LIST			0x04
+#define NVME_CNS_ALLOCATED_NAMESPACE_ID_LIST	0x10
+#define NVME_CNS_ID_ALLOCATED_NAMESPACE		0x11
+#define NVME_CNS_CONTROLLER_LIST_ATTACHED	0x12
+#define NVME_CNS_CONTROLLER_LIST		0x13
+#define NVME_CNS_PRIMARY_CONTROLLER_CAPABILITIES 0x14
+#define NVME_CNS_SECONDARY_CONTROLLER_LIST	0x15
+#define NVME_CNS_NAMESPACE_GRANULARITY_LIST	0x16
+#define NVME_CNS_UUID_LIST			0x17
+
 #define NVME_SERIAL_NUMBER_LENGTH	20
 #define NVME_MODEL_NUMBER_LENGTH	40
 #define NVME_FIRMWARE_REVISION_LENGTH	8
diff --git a/sys/dev/nvme/nvme_ctrlr_cmd.c b/sys/dev/nvme/nvme_ctrlr_cmd.c
--- a/sys/dev/nvme/nvme_ctrlr_cmd.c
+++ b/sys/dev/nvme/nvme_ctrlr_cmd.c
@@ -46,7 +46,7 @@
 	 * TODO: create an identify command data structure, which
 	 *  includes this CNS bit in cdw10.
 	 */
-	cmd->cdw10 = htole32(1);
+	cmd->cdw10 = htole32(NVME_CNS_ID_CONTROLLER);
 
 	nvme_ctrlr_submit_admin_request(ctrlr, req);
 }
diff --git a/sys/dev/nvmf/controller/nvmft_controller.c b/sys/dev/nvmf/controller/nvmft_controller.c
--- a/sys/dev/nvmf/controller/nvmft_controller.c
+++ b/sys/dev/nvmf/controller/nvmft_controller.c
@@ -669,11 +669,11 @@
 	}
 
 	switch (cns) {
-	case 0:	/* Namespace data. */
-	case 3:	/* Namespace Identification Descriptor list. */
+	case NVME_CNS_ID_NAMESPACE:	/* Namespace data. */
+	case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST:	/* Namespace Identification Descriptor list. */
 		nvmft_dispatch_command(ctrlr->admin, nc, true);
 		return;
-	case 1:
+	case NVME_CNS_ID_CONTROLLER:
 		/* Controller data. */
 		m = m_getml(sizeof(ctrlr->cdata), M_WAITOK);
 		m_copyback(m, 0, sizeof(ctrlr->cdata), (void *)&ctrlr->cdata);
@@ -681,7 +681,7 @@
 		    sizeof(ctrlr->cdata));
 		MPASS(status != NVMF_MORE);
 		break;
-	case 2:
+	case NVME_CNS_ACTIVE_NAMESPACE_ID_LIST:
 	{
 		/* Active namespace list. */
 		struct nvme_ns_list *nslist;
diff --git a/sys/dev/nvmf/host/nvmf_cmd.c b/sys/dev/nvmf/host/nvmf_cmd.c
--- a/sys/dev/nvmf/host/nvmf_cmd.c
+++ b/sys/dev/nvmf/host/nvmf_cmd.c
@@ -100,7 +100,7 @@
 	cmd.opc = NVME_OPC_IDENTIFY;
 
 	/* 5.15.1 Use CNS of 0x02 for namespace data. */
-	cmd.cdw10 = htole32(2);
+	cmd.cdw10 = htole32(NVME_CNS_ACTIVE_NAMESPACE_ID_LIST);
 	cmd.nsid = htole32(id);
 
 	req = nvmf_allocate_request(sc->admin, &cmd, req_cb, req_cb_arg, how);
@@ -126,7 +126,7 @@
 	cmd.opc = NVME_OPC_IDENTIFY;
 
 	/* 5.15.1 Use CNS of 0x00 for namespace data. */
-	cmd.cdw10 = htole32(0);
+	cmd.cdw10 = htole32(NVME_CNS_ID_NAMESPACE);
 	cmd.nsid = htole32(id);
 
 	req = nvmf_allocate_request(sc->admin, &cmd, req_cb, req_cb_arg, how);
diff --git a/usr.sbin/bhyve/pci_nvme.c b/usr.sbin/bhyve/pci_nvme.c
--- a/usr.sbin/bhyve/pci_nvme.c
+++ b/usr.sbin/bhyve/pci_nvme.c
@@ -1497,7 +1497,7 @@
 	pci_nvme_status_genc(&status, NVME_SC_SUCCESS);
 
 	switch (command->cdw10 & 0xFF) {
-	case 0x00: /* return Identify Namespace data structure */
+	case NVME_CNS_ID_NAMESPACE: /* return Identify Namespace data structure */
 		/* Global NS only valid with NS Management */
 		if (command->nsid == NVME_GLOBAL_NAMESPACE_TAG) {
 			pci_nvme_status_genc(&status,
@@ -1508,20 +1508,20 @@
 		    command->prp2, (uint8_t *)&sc->nsdata, sizeof(sc->nsdata),
 		    NVME_COPY_TO_PRP);
 		break;
-	case 0x01: /* return Identify Controller data structure */
+	case NVME_CNS_ID_CONTROLLER: /* return Identify Controller data structure */
 		nvme_prp_memcpy(sc->nsc_pi->pi_vmctx, command->prp1,
 		    command->prp2, (uint8_t *)&sc->ctrldata,
 		    sizeof(sc->ctrldata),
 		    NVME_COPY_TO_PRP);
 		break;
-	case 0x02: /* list of 1024 active NSIDs > CDW1.NSID */
+	case NVME_CNS_ACTIVE_NAMESPACE_ID_LIST: /* list of 1024 active NSIDs > CDW1.NSID */
 		dest = vm_map_gpa(sc->nsc_pi->pi_vmctx, command->prp1,
 		                  sizeof(uint32_t) * 1024);
 		/* All unused entries shall be zero */
 		memset(dest, 0, sizeof(uint32_t) * 1024);
 		((uint32_t *)dest)[0] = 1;
 		break;
-	case 0x03: /* list of NSID structures in CDW1.NSID, 4096 bytes */
+	case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST: /* list of NSID structures in CDW1.NSID, 4096 bytes */
 		if (command->nsid != 1) {
 			pci_nvme_status_genc(&status,
 			    NVME_SC_INVALID_NAMESPACE_OR_FORMAT);
@@ -1537,7 +1537,7 @@
 		((uint8_t *)dest)[1] = sizeof(uint64_t);
 		memcpy(((uint8_t *)dest) + 4, sc->nsdata.eui64, sizeof(uint64_t));
 		break;
-	case 0x13:
+	case NVME_CNS_CONTROLLER_LIST:
 		/*
 		 * Controller list is optional but used by UNH tests. Return
 		 * a valid but empty list.
diff --git a/usr.sbin/camdd/camdd.c b/usr.sbin/camdd/camdd.c
--- a/usr.sbin/camdd/camdd.c
+++ b/usr.sbin/camdd/camdd.c
@@ -1398,7 +1398,7 @@
 	nc->opc = NVME_OPC_IDENTIFY;
 
 	nc->nsid = nsid;
-	nc->cdw10 = 0; /* Identify Namespace is CNS = 0 */
+	nc->cdw10 = NVME_CNS_ID_NAMESPACE; /* Identify Namespace is CNS = 0 */
 
 	cam_fill_nvmeadmin(&ccb->nvmeio,
 			/*retries*/ probe_retry_count,
diff --git a/usr.sbin/nvmfd/controller.c b/usr.sbin/nvmfd/controller.c
--- a/usr.sbin/nvmfd/controller.c
+++ b/usr.sbin/nvmfd/controller.c
@@ -154,7 +154,7 @@
 
 	cns = le32toh(cmd->cdw10) & 0xFF;
 	switch (cns) {
-	case 1:
+	case NVME_CNS_ID_CONTROLLER:
 		break;
 	default:
 		warnx("Unsupported CNS %#x for IDENTIFY", cns);
diff --git a/usr.sbin/nvmfd/io.c b/usr.sbin/nvmfd/io.c
--- a/usr.sbin/nvmfd/io.c
+++ b/usr.sbin/nvmfd/io.c
@@ -149,7 +149,7 @@
 
 	cns = le32toh(cmd->cdw10) & 0xFF;
 	switch (cns) {
-	case 0:	/* Namespace data. */
+	case NVME_CNS_ID_NAMESPACE:	/* Namespace data. */
 		if (!device_namespace_data(le32toh(cmd->nsid), &nsdata)) {
 			nvmf_send_generic_error(nc,
 			    NVME_SC_INVALID_NAMESPACE_OR_FORMAT);
@@ -158,7 +158,7 @@
 
 		nvmf_send_controller_data(nc, &nsdata, sizeof(nsdata));
 		return (true);
-	case 2:	/* Active namespace list. */
+	case NVME_CNS_ACTIVE_NAMESPACE_ID_LIST:	/* Active namespace list. */
 		nsid = le32toh(cmd->nsid);
 		if (nsid >= 0xfffffffe) {
 			nvmf_send_generic_error(nc, NVME_SC_INVALID_FIELD);
@@ -168,7 +168,7 @@
 		device_active_nslist(nsid, &nslist);
 		nvmf_send_controller_data(nc, &nslist, sizeof(nslist));
 		return (true);
-	case 3:	/* Namespace Identification Descriptor list. */
+	case NVME_CNS_NAMESPACE_ID_DESCRIPTOR_LIST:	/* Namespace Identification Descriptor list. */
 		if (!device_identification_descriptor(le32toh(cmd->nsid),
 		    &nsdata)) {
 			nvmf_send_generic_error(nc,