diff --git a/lib/libbhyve/Makefile b/lib/libbhyve/Makefile
--- a/lib/libbhyve/Makefile
+++ b/lib/libbhyve/Makefile
@@ -3,6 +3,7 @@
 PACKAGE=lib${LIB}
 LIB=	bhyve
 SRCS=	config.c 	\
+	net_backends.c	\
 	pci.c
 INCS=	bhyve/config.h		\
 	bhyve/net_backends.h	\
diff --git a/lib/libbhyve/net_backends.c b/lib/libbhyve/net_backends.c
new file mode 100644
--- /dev/null
+++ b/lib/libbhyve/net_backends.c
@@ -0,0 +1,364 @@
+/*
+ *
+ * Copyright (c) 2019 Vincenzo Maffione <vmaffione@FreeBSD.org>
+ * Copyright (c) 2023 Mark Johnston <markj@FreeBSD.org>
+ * Copyright (c) 2025 Bojan Novković <bnovkov@FreeBSD.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/param.h>
+#include <sys/nv.h>
+#include <sys/nv_namespace.h>
+#include <sys/socket.h>
+#include <sys/procdesc.h>
+
+#include <net/if.h>
+#include <net/netmap.h>
+#include <net/netmap_virt.h>
+#define NETMAP_WITH_LIBS
+#include <net/netmap_user.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <netgraph.h>
+#include <spawn.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "bhyve/config.h"
+#include "bhyve/net_backends.h"
+#include "bhyve/pci.h"
+#include "internal.h"
+
+struct netbe_info {
+	const char *prefix;
+	int (*init_fds)(nvlist_t *);
+	bool (*validate_hotplug_request)(nvlist_t *);
+};
+
+extern char **environ;
+
+static int
+slirp_init_fds(nvlist_t *nvl)
+{
+	int error;
+	pid_t child;
+	int child_pd;
+	const char **argv;
+	char sockname[32];
+	int sockpair_fds[2];
+	posix_spawnattr_t attr;
+	posix_spawn_file_actions_t fa;
+
+	error = socketpair(PF_LOCAL, SOCK_SEQPACKET | SOCK_NONBLOCK, 0,
+	    sockpair_fds);
+	if (error != 0) {
+		nvlist_add_stringf(nvl, "error", "Unable to create pipe: %s",
+		    strerror(errno));
+		return (error);
+	}
+
+	/*
+	 * The child will exit once its connection goes away, so make sure only
+	 * one end is inherited by the child.
+	 */
+	if (posix_spawn_file_actions_init(&fa) != 0) {
+		nvlist_add_string(nvl, "error",
+		    "posix_spawn_file_actions_init");
+		return (error);
+	}
+	if (posix_spawn_file_actions_addclose(&fa, sockpair_fds[0]) != 0) {
+		nvlist_add_string(nvl, "error",
+		    "posix_spawn_file_actions_addclose");
+		posix_spawn_file_actions_destroy(&fa);
+		return (error);
+	}
+	if (posix_spawnattr_init(&attr) != 0) {
+		nvlist_add_string(nvl, "error", "posix_spawnattr_init");
+		posix_spawn_file_actions_destroy(&fa);
+		return (error);
+	}
+	if (posix_spawnattr_setprocdescp_np(&attr, &child_pd, PD_CLOEXEC) != 0) {
+		nvlist_add_string(nvl, "error",
+		    "posix_spawnattr_setprocdescp_np");
+		posix_spawn_file_actions_destroy(&fa);
+		posix_spawnattr_destroy(&attr);
+		return (error);
+	}
+	(void)snprintf(sockname, sizeof(sockname), "%d", sockpair_fds[1]);
+	argv = (const char *[]){
+	    "/usr/libexec/bhyve-slirp-helper", "-S", sockname, NULL
+	};
+	child_pd = -1;
+	error = posix_spawn(&child, "/usr/libexec/bhyve-slirp-helper",
+	    &fa, &attr, __DECONST(char **, argv), environ);
+	posix_spawn_file_actions_destroy(&fa);
+	posix_spawnattr_destroy(&attr);
+	if (error != 0) {
+		nvlist_add_stringf(nvl, "error", "posix_spawn(bhyve-slirp-helper): %s",
+		    strerror(error));
+		return (error);
+	}
+	assert(child_pd != -1);
+
+	nvlist_add_descriptor_array(nvl, "sockpair", sockpair_fds,
+	    nitems(sockpair_fds));
+	nvlist_add_descriptor(nvl, "helper_pd", child_pd);
+
+	return (0);
+}
+
+static bool
+slirp_validate_hotplug_request(nvlist_t *nvl)
+{
+	if (!nvlist_exists_descriptor_array(nvl, "sockpair")) {
+		nvlist_add_string(nvl, "error",
+		    "missing socket descriptor pair");
+		return (false);
+	}
+
+	if (!nvlist_exists_descriptor(nvl, "helper_pd")) {
+		nvlist_add_string(nvl, "error",
+		    "missing slirp helper process descriptor");
+		return (false);
+	}
+
+	return (true);
+}
+
+static int
+tap_init_fds(nvlist_t *nvl)
+{
+	int fd;
+	char tbuf[80];
+	const char *devname;
+
+	if (!nvlist_exists_string(nvl, "backend")) {
+		nvlist_add_string(nvl, "error", "missing backend parameter");
+		return (-1);
+	}
+
+	devname = nvlist_get_string(nvl, "backend");
+	strcpy(tbuf, "/dev/");
+	strlcat(tbuf, devname, sizeof(tbuf));
+	fd = open(tbuf, O_RDWR);
+	if (fd == -1) {
+		nvlist_add_stringf(nvl, "error",
+		    "open of tap device %s failed: %s", tbuf, strerror(errno));
+		return (-1);
+	}
+	nvlist_move_descriptor(nvl, "devfd", fd);
+
+	return (0);
+}
+
+static bool
+tap_validate_hotplug_request(nvlist_t *nvl)
+{
+	if (!nvlist_exists_descriptor(nvl, "devfd")) {
+		nvlist_add_string(nvl, "error",
+		    "missing tap device file descriptor");
+		return (false);
+	}
+	return (true);
+}
+
+static int
+ng_init_fds(nvlist_t *nvl)
+{
+	int csp, dsp;
+	const char *nodename;
+
+	if (!nvlist_exists_string(nvl, "socket")) {
+		nvlist_add_string(nvl, "error", "missing socket path");
+		return (-1);
+	}
+	nodename = nvlist_get_string(nvl, "socket");
+	if (NgMkSockNode(nodename, &csp, &dsp) < 0) {
+		nvlist_add_stringf(nvl, "error", "can't get Netgraph sockets");
+		return (-1);
+	}
+
+	nvlist_move_descriptor(nvl, "csp", csp);
+	nvlist_move_descriptor(nvl, "dsp", dsp);
+
+	return (0);
+}
+
+static bool
+ng_validate_hotplug_request(nvlist_t *nvl)
+{
+	if (!nvlist_exists_descriptor(nvl, "csp")) {
+		nvlist_add_string(nvl, "error",
+		    "missing control socket descriptor");
+		return (false);
+	}
+	if (!nvlist_exists_descriptor(nvl, "dsp")) {
+		nvlist_add_string(nvl, "error",
+		    "missing data socket descriptor");
+		return (false);
+	}
+
+	return (true);
+}
+
+static int
+netmap_init_fds(nvlist_t *nvl)
+{
+	struct nm_desc *nmd;
+	const char *devname;
+
+	if (!nvlist_exists_string(nvl, "backend")) {
+		nvlist_add_string(nvl, "error", "missing backend parameter");
+		return (-1);
+	}
+	devname = nvlist_get_string(nvl, "backend");
+	nmd = nm_open(devname, NULL, NETMAP_NO_TX_POLL, NULL);
+	if (nmd == NULL) {
+		nvlist_add_stringf(nvl, "error",
+		    "Unable to nm_open(): interface '%s', errno (%s)", devname,
+		    strerror(errno));
+		return (-1);
+	}
+	nvlist_move_binary(nvl, "nm_desc", nmd, sizeof(*nmd));
+
+	return (0);
+}
+
+static bool
+netmap_validate_hotplug_request(nvlist_t *nvl)
+{
+	size_t size;
+	struct nm_desc *nmd;
+
+	if (!nvlist_exists_binary(nvl, "nm_desc")) {
+		nvlist_add_string(nvl, "error",
+		    "missing netmap descriptor structure");
+		return (false);
+	}
+
+	(void)nvlist_get_binary(nvl, "nm_desc", &size);
+	if (size != sizeof(*nmd)) {
+		nvlist_add_string(nvl, "error",
+		    "mismatched netmap descriptor structure size");
+		return (false);
+	}
+
+	return (true);
+}
+
+static struct netbe_info netbe_tap = {
+	.prefix = "tap",
+	.init_fds = tap_init_fds,
+	.validate_hotplug_request = tap_validate_hotplug_request
+};
+
+static struct netbe_info netbe_ngd = {
+	.prefix = "ngd",
+	.init_fds = tap_init_fds,
+	.validate_hotplug_request = tap_validate_hotplug_request
+};
+
+static struct netbe_info netbe_netmap = {
+	.prefix = "netmap",
+	.init_fds = netmap_init_fds,
+	.validate_hotplug_request = netmap_validate_hotplug_request
+};
+
+static struct netbe_info netbe_netgraph = {
+	.prefix = "netgraph",
+	.init_fds = ng_init_fds,
+	.validate_hotplug_request = ng_validate_hotplug_request
+};
+
+static struct netbe_info netbe_slirp = {
+	.prefix = "slirp",
+	.init_fds = slirp_init_fds,
+	.validate_hotplug_request = slirp_validate_hotplug_request
+};
+
+SET_DECLARE(net_backends_info, struct netbe_info);
+DATA_SET(net_backends_info, netbe_netgraph);
+DATA_SET(net_backends_info, netbe_slirp);
+DATA_SET(net_backends_info, netbe_netmap);
+DATA_SET(net_backends_info, netbe_tap);
+DATA_SET(net_backends_info, netbe_ngd);
+
+static struct netbe_info *
+find_netbe_info(const char *backend)
+{
+	struct netbe_info **nbe;
+
+	SET_FOREACH(nbe, net_backends_info) {
+		if (strncmp(backend, (*nbe)->prefix,
+		    strlen((*nbe)->prefix)) == 0) {
+			return (*nbe);
+		}
+	}
+	return (NULL);
+}
+
+int
+netbe_init_fds(nvlist_t *nvl)
+{
+	const char *backend;
+	struct netbe_info *nbi;
+
+	if (!nvlist_exists_string(nvl, "backend")) {
+		nvlist_add_string(nvl, "error", "missing backend argument");
+		return (-1);
+	}
+	backend = nvlist_get_string(nvl, "backend");
+	nbi = find_netbe_info(backend);
+	if (nbi == NULL) {
+		nvlist_add_stringf(nvl, "error", "unknown backend '%s'",
+		    backend);
+		return (-1);
+	}
+
+	if (nbi->init_fds == NULL)
+		return (0);
+
+	return (nbi->init_fds(nvl));
+}
+
+int
+netbe_legacy_config(nvlist_t *nvl, const char *opts)
+{
+	char *backend, *cp;
+
+	if (opts == NULL)
+		return (0);
+
+	cp = strchr(opts, ',');
+	if (cp == NULL) {
+		set_config_value_node(nvl, "backend", opts);
+		return (0);
+	}
+	backend = strndup(opts, cp - opts);
+	set_config_value_node(nvl, "backend", backend);
+	free(backend);
+	return (pci_parse_legacy_config(nvl, cp + 1));
+}
+
+bool
+netbe_validate_hotplug_request(nvlist_t *nvl)
+{
+	const char *backend;
+	struct netbe_info *nbi;
+
+	if (!nvlist_exists_string(nvl, "backend")) {
+		nvlist_add_string(nvl, "error", "missing backend argument");
+		return (-1);
+	}
+	backend = nvlist_get_string(nvl, "backend");
+	nbi = find_netbe_info(backend);
+
+	if (nbi == NULL || nbi->validate_hotplug_request == NULL)
+		return (0);
+
+	return (nbi->validate_hotplug_request(nvl));
+}
diff --git a/usr.sbin/bhyve/net_backend_netgraph.c b/usr.sbin/bhyve/net_backend_netgraph.c
--- a/usr.sbin/bhyve/net_backend_netgraph.c
+++ b/usr.sbin/bhyve/net_backend_netgraph.c
@@ -53,7 +53,7 @@
 {
 	struct tap_priv *p = NET_BE_PRIV(be);
 	struct ngm_connect ngc;
-	const char *value, *nodename;
+	const char *value;
 	int sbsz;
 	int ctrl_sock;
 	int flags;
@@ -74,7 +74,7 @@
 
 	value = get_config_value_node(nvl, "path");
 	if (value == NULL) {
-		EPRINTLN("path must be provided");
+		nvlist_add_string(nvl, "error", "path must be provided");
 		return (-1);
 	}
 	strncpy(ngc.path, value, NG_PATHSIZ - 1);
@@ -86,22 +86,18 @@
 
 	value = get_config_value_node(nvl, "peerhook");
 	if (value == NULL) {
-		EPRINTLN("peer hook must be provided");
+		nvlist_add_string(nvl, "error", "peer hook must be provided");
 		return (-1);
 	}
 	strncpy(ngc.peerhook, value, NG_HOOKSIZ - 1);
 
-	nodename = get_config_value_node(nvl, "socket");
-	if (NgMkSockNode(nodename,
-		&ctrl_sock, &be->fd) < 0) {
-		EPRINTLN("can't get Netgraph sockets");
-		return (-1);
-	}
+	ctrl_sock = nvlist_take_descriptor(nvl, "csp");
+	be->fd = nvlist_take_descriptor(nvl, "dsp");
 
 	if (NgSendMsg(ctrl_sock, ".",
 		NGM_GENERIC_COOKIE,
 		NGM_CONNECT, &ngc, sizeof(ngc)) < 0) {
-		EPRINTLN("can't connect to node");
+		nvlist_add_string(nvl, "error", "can't connect to node");
 		close(ctrl_sock);
 		goto error;
 	}
@@ -111,12 +107,12 @@
 	flags = fcntl(be->fd, F_GETFL);
 
 	if (flags < 0) {
-		EPRINTLN("can't get socket flags");
+		nvlist_add_string(nvl, "error", "can't get socket flags");
 		goto error;
 	}
 
 	if (fcntl(be->fd, F_SETFL, flags | O_NONBLOCK) < 0) {
-		EPRINTLN("can't set O_NONBLOCK flag");
+		nvlist_add_string(nvl, "error", "can't set O_NONBLOCK flag");
 		goto error;
 	}
 
@@ -128,7 +124,8 @@
 	msbsz = sizeof(maxsbsz);
 	if (sysctlbyname("kern.ipc.maxsockbuf", &maxsbsz, &msbsz,
 		NULL, 0) < 0) {
-		EPRINTLN("can't get 'kern.ipc.maxsockbuf' value");
+		nvlist_add_string(nvl, "error",
+		    "can't get 'kern.ipc.maxsockbuf' value");
 		goto error;
 	}
 
@@ -142,13 +139,13 @@
 
 	if (setsockopt(be->fd, SOL_SOCKET, SO_SNDBUF, &sbsz,
 		sizeof(sbsz)) < 0) {
-		EPRINTLN("can't set TX buffer size");
+		nvlist_add_string(nvl, "error", "can't set TX buffer size");
 		goto error;
 	}
 
 	if (setsockopt(be->fd, SOL_SOCKET, SO_RCVBUF, &sbsz,
 		sizeof(sbsz)) < 0) {
-		EPRINTLN("can't set RX buffer size");
+		nvlist_add_string(nvl, "error", "can't set RX buffer size");
 		goto error;
 	}
 
@@ -163,7 +160,7 @@
 
 	p->mevp = mevent_add_disabled(be->fd, EVF_READ, cb, param);
 	if (p->mevp == NULL) {
-		EPRINTLN("Could not register event");
+		nvlist_add_string(nvl, "error", "Could not register event");
 		goto error;
 	}
 
diff --git a/usr.sbin/bhyve/net_backend_netmap.c b/usr.sbin/bhyve/net_backend_netmap.c
--- a/usr.sbin/bhyve/net_backend_netmap.c
+++ b/usr.sbin/bhyve/net_backend_netmap.c
@@ -123,21 +123,15 @@
 }
 
 static int
-netmap_init(struct net_backend *be, const char *devname,
-    nvlist_t *nvl __unused, net_be_rxeof_t cb, void *param)
+netmap_init(struct net_backend *be, const char *devname, nvlist_t *nvl,
+    net_be_rxeof_t cb, void *param)
 {
 	struct netmap_priv *priv = NET_BE_PRIV(be);
+	size_t size;
 
 	strlcpy(priv->ifname, devname, sizeof(priv->ifname));
 	priv->ifname[sizeof(priv->ifname) - 1] = '\0';
-
-	priv->nmd = nm_open(priv->ifname, NULL, NETMAP_NO_TX_POLL, NULL);
-	if (priv->nmd == NULL) {
-		EPRINTLN("Unable to nm_open(): interface '%s', errno (%s)",
-		    devname, strerror(errno));
-		return (-1);
-	}
-
+	priv->nmd = nvlist_take_binary(nvl, "nm_desc", &size);
 	priv->memid = priv->nmd->req.nr_arg2;
 	priv->tx = NETMAP_TXRING(priv->nmd->nifp, 0);
 	priv->rx = NETMAP_RXRING(priv->nmd->nifp, 0);
@@ -147,7 +141,7 @@
 
 	priv->mevp = mevent_add_disabled(be->fd, EVF_READ, cb, param);
 	if (priv->mevp == NULL) {
-		EPRINTLN("Could not register event");
+		nvlist_add_string(nvl, "error", "Could not register event");
 		return (-1);
 	}
 
diff --git a/usr.sbin/bhyve/net_backend_slirp.c b/usr.sbin/bhyve/net_backend_slirp.c
--- a/usr.sbin/bhyve/net_backend_slirp.c
+++ b/usr.sbin/bhyve/net_backend_slirp.c
@@ -47,6 +47,7 @@
  * thread also handles timeout events from the libslirp context.
  */
 
+#include <sys/procdesc.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
 
@@ -84,57 +85,31 @@
 {
 	struct slirp_priv *priv = NET_BE_PRIV(be);
 	nvlist_t *config;
-	posix_spawn_file_actions_t fa;
 	pid_t child;
-	const char **argv;
-	char sockname[32];
-	int error, s[2];
+	int error, *s;
+	size_t mtu, nitems;
 	const char *mtu_value;
-	size_t mtu;
+	int helper_pd;
 
-	if (socketpair(PF_LOCAL, SOCK_SEQPACKET | SOCK_NONBLOCK, 0, s) != 0) {
-		EPRINTLN("socketpair");
+	s = nvlist_take_descriptor_array(nvl, "sockpair", &nitems);
+	if (nitems != 2) {
+		nvlist_add_string(nvl, "error",
+		    "mismatched number of socket descriptors");
 		return (-1);
 	}
 
-	/*
-	 * The child will exit once its connection goes away, so make sure only
-	 * one end is inherited by the child.
-	 */
-	if (posix_spawn_file_actions_init(&fa) != 0) {
-		EPRINTLN("posix_spawn_file_actions_init");
-		goto err;
-	}
-	if (posix_spawn_file_actions_addclose(&fa, s[0]) != 0) {
-		EPRINTLN("posix_spawn_file_actions_addclose");
-		posix_spawn_file_actions_destroy(&fa);
-		goto err;
-	}
-
-	(void)snprintf(sockname, sizeof(sockname), "%d", s[1]);
-	argv = (const char *[]){
-	    "/usr/libexec/bhyve-slirp-helper", "-S", sockname, NULL
-	};
-	error = posix_spawn(&child, "/usr/libexec/bhyve-slirp-helper",
-	    &fa, NULL, __DECONST(char **, argv), environ);
-	posix_spawn_file_actions_destroy(&fa);
-	if (error != 0) {
-		EPRINTLN("posix_spawn(bhyve-slirp-helper): %s",
-		    strerror(error));
-		goto err;
-	}
-
 	config = nvlist_clone(nvl);
 	if (config == NULL) {
-		EPRINTLN("nvlist_clone");
+		nvlist_add_string(nvl, "error",
+		    "nvlist_clone");
 		goto err;
 	}
 
 	mtu_value = get_config_value_node(config, "mtu");
 	if (mtu_value != NULL) {
 		if (net_parsemtu(mtu_value, &mtu)) {
-		    	EPRINTLN("Could not parse MTU");
-		    	goto err;
+			nvlist_add_string(nvl, "error", "Could not parse MTU");
+			goto err;
 		}
 	} else {
 		mtu = DEFAULT_MTU;
@@ -144,7 +119,7 @@
 	priv->mtu = mtu;
 	priv->buf = malloc(mtu);
 	if (priv->buf == NULL) {
-		EPRINTLN("Could not allocate buffer");
+		nvlist_add_string(nvl, "error", "Could not allocate MTU buffer");
 		goto err;
 	}
 
@@ -152,14 +127,21 @@
 	error = nvlist_send(s[0], config);
 	nvlist_destroy(config);
 	if (error != 0) {
-		EPRINTLN("nvlist_send");
+		nvlist_add_string(nvl, "error",
+		    "nvlist_send");
 		goto err;
 	}
 
 	be->fd = s[0];
 	priv->mevp = mevent_add_disabled(be->fd, EVF_READ, cb, param);
 	if (priv->mevp == NULL) {
-		EPRINTLN("Could not register event");
+		nvlist_add_string(nvl, "error", "Could not register event");
+		goto err;
+	}
+	helper_pd = nvlist_take_descriptor(nvl, "helper_pd");
+	if (pdgetpid(helper_pd, &child) != 0) {
+		nvlist_add_string(nvl, "error",
+		    "pdgetpid failed");
 		goto err;
 	}
 
diff --git a/usr.sbin/bhyve/net_backends.c b/usr.sbin/bhyve/net_backends.c
--- a/usr.sbin/bhyve/net_backends.c
+++ b/usr.sbin/bhyve/net_backends.c
@@ -85,11 +85,10 @@
 }
 
 static int
-tap_init(struct net_backend *be, const char *devname,
-    nvlist_t *nvl __unused, net_be_rxeof_t cb, void *param)
+tap_init(struct net_backend *be, const char *devname __unused, nvlist_t *nvl,
+    net_be_rxeof_t cb, void *param)
 {
 	struct tap_priv *priv = NET_BE_PRIV(be);
-	char tbuf[80];
 	int opt = 1, up = IFF_UP;
 
 #ifndef WITHOUT_CAPSICUM
@@ -97,31 +96,25 @@
 #endif
 
 	if (cb == NULL) {
-		EPRINTLN("TAP backend requires non-NULL callback");
+		nvlist_add_string(nvl, "error",
+		    "TAP backend requires non-NULL callback");
 		return (-1);
 	}
 
-	strcpy(tbuf, "/dev/");
-	strlcat(tbuf, devname, sizeof(tbuf));
-
-	be->fd = open(tbuf, O_RDWR);
-	if (be->fd == -1) {
-		EPRINTLN("open of tap device %s failed", tbuf);
-		goto error;
-	}
+	be->fd = nvlist_take_descriptor(nvl, "devfd");
 
 	/*
 	 * Set non-blocking and register for read
 	 * notifications with the event loop
 	 */
 	if (ioctl(be->fd, FIONBIO, &opt) < 0) {
-		EPRINTLN("tap device O_NONBLOCK failed");
+		nvlist_add_string(nvl, "error", "tap device O_NONBLOCK failed");
 		goto error;
 	}
 
 	if (strncmp("ngd", be->prefix, 3) &&
 	    ioctl(be->fd, VMIO_SIOCSIFFLAGS, up)) {
-		EPRINTLN("tap device link up failed");
+		nvlist_add_string(nvl, "error", "tap device link up failed");
 		goto error;
 	}
 
@@ -136,7 +129,7 @@
 
 	priv->mevp = mevent_add_disabled(be->fd, EVF_READ, cb, param);
 	if (priv->mevp == NULL) {
-		EPRINTLN("Could not register event");
+		nvlist_add_string(nvl, "error", "Could not register event");
 		goto error;
 	}
 
@@ -293,25 +286,6 @@
 DATA_SET(net_backend_set, vmnet_backend);
 DATA_SET(net_backend_set, ngd_backend);
 
-int
-netbe_legacy_config(nvlist_t *nvl, const char *opts)
-{
-	char *backend, *cp;
-
-	if (opts == NULL)
-		return (0);
-
-	cp = strchr(opts, ',');
-	if (cp == NULL) {
-		set_config_value_node(nvl, "backend", opts);
-		return (0);
-	}
-	backend = strndup(opts, cp - opts);
-	set_config_value_node(nvl, "backend", backend);
-	free(backend);
-	return (pci_parse_legacy_config(nvl, cp + 1));
-}
-
 /*
  * Initialize a backend and attach to the frontend.
  * This is called during frontend initialization.
@@ -335,6 +309,7 @@
 
 	value = get_config_value_node(nvl, "backend");
 	if (value == NULL) {
+		nvlist_add_string(nvl, "error", "missing backend argument");
 		return (-1);
 	}
 	devname = strdup(value);
@@ -367,6 +342,7 @@
 
 	*ret = NULL;
 	if (tbe == NULL) {
+		nvlist_add_stringf(nvl, "error", "unknown backend '%s'", type);
 		free(devname);
 		return (EINVAL);
 	}