Merge remote-tracking branch 'remotes/stefanha/tags/net-pull-request' into staging

# gpg: Signature made Wed May 27 11:02:55 2015 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/net-pull-request:
  net/net: Record usage status of mac address
  tap: Improve -netdev/netdev_add/-net/... tap error reporting
  tap: Finish conversion of tap_open() to Error
  tap-solaris: Convert tap_open() to Error
  tap-bsd: Convert tap_open() to Error
  tap-linux: Convert tap_open() to Error
  tap: Permit incremental conversion of tap_open() to Error
  tap: Convert launch_script() to Error
  tap: Convert net_init_tap_one() to Error
  tap: Convert tap_set_sndbuf() to Error
  tap: Improve -netdev/netdev_add/-net/... bridge error reporting
  tap: net_tap_fd_init() can't fail, drop dead error handling
  net/dump: Improve -net/host_net_add dump error reporting
  net: Improve -net nic error reporting
  net: Permit incremental conversion of init functions to Error
  net: Improve error message for -net hubport a bit
  net: Change help text to list -netdev instead of -net by default

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

19 files changed, 331 insertions, 239 deletions

diff --git a/net/clients.h b/net/clients.h
index 2e8feda..d47530e 100644
--- a/net/clients.h
+++ b/net/clients.h
@@ -28,38 +28,38 @@
 #include "qapi-types.h"
 
 int net_init_dump(const NetClientOptions *opts, const char *name,
-                  NetClientState *peer);
+                  NetClientState *peer, Error **errp);
 
 #ifdef CONFIG_SLIRP
 int net_init_slirp(const NetClientOptions *opts, const char *name,
-                   NetClientState *peer);
+                   NetClientState *peer, Error **errp);
 #endif
 
 int net_init_hubport(const NetClientOptions *opts, const char *name,
-                     NetClientState *peer);
+                     NetClientState *peer, Error **errp);
 
 int net_init_socket(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer);
+                    NetClientState *peer, Error **errp);
 
 int net_init_tap(const NetClientOptions *opts, const char *name,
-                 NetClientState *peer);
+                 NetClientState *peer, Error **errp);
 
 int net_init_bridge(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer);
+                    NetClientState *peer, Error **errp);
 
 int net_init_l2tpv3(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer);
+                    NetClientState *peer, Error **errp);
 #ifdef CONFIG_VDE
 int net_init_vde(const NetClientOptions *opts, const char *name,
-                 NetClientState *peer);
+                 NetClientState *peer, Error **errp);
 #endif
 
 #ifdef CONFIG_NETMAP
 int net_init_netmap(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer);
+                    NetClientState *peer, Error **errp);
 #endif
 
 int net_init_vhost_user(const NetClientOptions *opts, const char *name,
-                        NetClientState *peer);
+                        NetClientState *peer, Error **errp);
 
 #endif /* QEMU_NET_CLIENTS_H */
diff --git a/net/dump.c b/net/dump.c
index 9d3a09e..02c8064 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -101,7 +101,8 @@ static NetClientInfo net_dump_info = {
 };
 
 static int net_dump_init(NetClientState *peer, const char *device,
-                         const char *name, const char *filename, int len)
+                         const char *name, const char *filename, int len,
+                         Error **errp)
 {
     struct pcap_file_hdr hdr;
     NetClientState *nc;
@@ -111,7 +112,7 @@ static int net_dump_init(NetClientState *peer, const char *device,
 
     fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY | O_BINARY, 0644);
     if (fd < 0) {
-        error_report("-net dump: can't open %s", filename);
+        error_setg_errno(errp, errno, "-net dump: can't open %s", filename);
         return -1;
     }
 
@@ -124,7 +125,7 @@ static int net_dump_init(NetClientState *peer, const char *device,
     hdr.linktype = 1;
 
     if (write(fd, &hdr, sizeof(hdr)) < sizeof(hdr)) {
-        error_report("-net dump write error: %s", strerror(errno));
+        error_setg_errno(errp, errno, "-net dump write error");
         close(fd);
         return -1;
     }
@@ -146,7 +147,7 @@ static int net_dump_init(NetClientState *peer, const char *device,
 }
 
 int net_init_dump(const NetClientOptions *opts, const char *name,
-                  NetClientState *peer)
+                  NetClientState *peer, Error **errp)
 {
     int len;
     const char *file;
@@ -173,7 +174,7 @@ int net_init_dump(const NetClientOptions *opts, const char *name,
 
     if (dump->has_len) {
         if (dump->len > INT_MAX) {
-            error_report("invalid length: %"PRIu64, dump->len);
+            error_setg(errp, "invalid length: %"PRIu64, dump->len);
             return -1;
         }
         len = dump->len;
@@ -181,5 +182,5 @@ int net_init_dump(const NetClientOptions *opts, const char *name,
         len = 65536;
     }
 
-    return net_dump_init(peer, "dump", name, file, len);
+    return net_dump_init(peer, "dump", name, file, len, errp);
 }
diff --git a/net/hub.c b/net/hub.c
index 2b60ab9..3047f12 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -281,17 +281,14 @@ int net_hub_id_for_client(NetClientState *nc, int *id)
 }
 
 int net_init_hubport(const NetClientOptions *opts, const char *name,
-                     NetClientState *peer)
+                     NetClientState *peer, Error **errp)
 {
     const NetdevHubPortOptions *hubport;
 
     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_HUBPORT);
+    assert(!peer);
     hubport = opts->hubport;
 
-    if (peer) {
-        return -EINVAL;
-    }
-
     net_hub_add_port(hubport->hubid, name);
     return 0;
 }
diff --git a/net/l2tpv3.c b/net/l2tpv3.c
index 8c598b0..ed395dc 100644
--- a/net/l2tpv3.c
+++ b/net/l2tpv3.c
@@ -536,10 +536,9 @@ static NetClientInfo net_l2tpv3_info = {
 
 int net_init_l2tpv3(const NetClientOptions *opts,
                     const char *name,
-                    NetClientState *peer)
+                    NetClientState *peer, Error **errp)
 {
-
-
+    /* FIXME error_setg(errp, ...) on failure */
     const NetdevL2TPv3Options *l2tpv3;
     NetL2TPV3State *s;
     NetClientState *nc;
diff --git a/net/net.c b/net/net.c
index 7427f6a..db6be12 100644
--- a/net/net.c
+++ b/net/net.c
@@ -167,19 +167,68 @@ void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6])
              macaddr[3], macaddr[4], macaddr[5]);
 }
 
+static int mac_table[256] = {0};
+
+static void qemu_macaddr_set_used(MACAddr *macaddr)
+{
+    int index;
+
+    for (index = 0x56; index < 0xFF; index++) {
+        if (macaddr->a[5] == index) {
+            mac_table[index]++;
+        }
+    }
+}
+
+static void qemu_macaddr_set_free(MACAddr *macaddr)
+{
+    int index;
+    static const MACAddr base = { .a = { 0x52, 0x54, 0x00, 0x12, 0x34, 0 } };
+
+    if (memcmp(macaddr->a, &base.a, (sizeof(base.a) - 1)) != 0) {
+        return;
+    }
+    for (index = 0x56; index < 0xFF; index++) {
+        if (macaddr->a[5] == index) {
+            mac_table[index]--;
+        }
+    }
+}
+
+static int qemu_macaddr_get_free(void)
+{
+    int index;
+
+    for (index = 0x56; index < 0xFF; index++) {
+        if (mac_table[index] == 0) {
+            return index;
+        }
+    }
+
+    return -1;
+}
+
 void qemu_macaddr_default_if_unset(MACAddr *macaddr)
 {
-    static int index = 0;
     static const MACAddr zero = { .a = { 0,0,0,0,0,0 } };
+    static const MACAddr base = { .a = { 0x52, 0x54, 0x00, 0x12, 0x34, 0 } };
+
+    if (memcmp(macaddr, &zero, sizeof(zero)) != 0) {
+        if (memcmp(macaddr->a, &base.a, (sizeof(base.a) - 1)) != 0) {
+            return;
+        } else {
+            qemu_macaddr_set_used(macaddr);
+            return;
+        }
+    }
 
-    if (memcmp(macaddr, &zero, sizeof(zero)) != 0)
-        return;
     macaddr->a[0] = 0x52;
     macaddr->a[1] = 0x54;
     macaddr->a[2] = 0x00;
     macaddr->a[3] = 0x12;
     macaddr->a[4] = 0x34;
-    macaddr->a[5] = 0x56 + index++;
+    macaddr->a[5] = qemu_macaddr_get_free();
+    qemu_macaddr_set_used(macaddr);
 }
 
 /**
@@ -374,6 +423,8 @@ void qemu_del_nic(NICState *nic)
 {
     int i, queues = MAX(nic->conf->peers.queues, 1);
 
+    qemu_macaddr_set_free(&nic->conf->macaddr);
+
     /* If this is a peer NIC and peer has already been deleted, free it now. */
     if (nic->peer_deleted) {
         for (i = 0; i < queues; i++) {
@@ -740,7 +791,7 @@ int qemu_find_nic_model(NICInfo *nd, const char * const *models,
 }
 
 static int net_init_nic(const NetClientOptions *opts, const char *name,
-                        NetClientState *peer)
+                        NetClientState *peer, Error **errp)
 {
     int idx;
     NICInfo *nd;
@@ -751,7 +802,7 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
 
     idx = nic_get_free_idx();
     if (idx == -1 || nb_nics >= MAX_NICS) {
-        error_report("Too Many NICs");
+        error_setg(errp, "too many NICs");
         return -1;
     }
 
@@ -762,7 +813,7 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
     if (nic->has_netdev) {
         nd->netdev = qemu_find_netdev(nic->netdev);
         if (!nd->netdev) {
-            error_report("netdev '%s' not found", nic->netdev);
+            error_setg(errp, "netdev '%s' not found", nic->netdev);
             return -1;
         }
     } else {
@@ -779,19 +830,20 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
 
     if (nic->has_macaddr &&
         net_parse_macaddr(nd->macaddr.a, nic->macaddr) < 0) {
-        error_report("invalid syntax for ethernet address");
+        error_setg(errp, "invalid syntax for ethernet address");
         return -1;
     }
     if (nic->has_macaddr &&
         is_multicast_ether_addr(nd->macaddr.a)) {
-        error_report("NIC cannot have multicast MAC address (odd 1st byte)");
+        error_setg(errp,
+                   "NIC cannot have multicast MAC address (odd 1st byte)");
         return -1;
     }
     qemu_macaddr_default_if_unset(&nd->macaddr);
 
     if (nic->has_vectors) {
         if (nic->vectors > 0x7ffffff) {
-            error_report("invalid # of vectors: %"PRIu32, nic->vectors);
+            error_setg(errp, "invalid # of vectors: %"PRIu32, nic->vectors);
             return -1;
         }
         nd->nvectors = nic->vectors;
@@ -809,7 +861,7 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
 static int (* const net_client_init_fun[NET_CLIENT_OPTIONS_KIND_MAX])(
     const NetClientOptions *opts,
     const char *name,
-    NetClientState *peer) = {
+    NetClientState *peer, Error **errp) = {
         [NET_CLIENT_OPTIONS_KIND_NIC]       = net_init_nic,
 #ifdef CONFIG_SLIRP
         [NET_CLIENT_OPTIONS_KIND_USER]      = net_init_slirp,
@@ -882,6 +934,11 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
     } else {
         u.net = object;
         opts = u.net->opts;
+        if (opts->kind == NET_CLIENT_OPTIONS_KIND_HUBPORT) {
+            error_set(errp, QERR_INVALID_PARAMETER_VALUE, "type",
+                      "a net type");
+            return -1;
+        }
         /* missing optional values have been initialized to "all bits zero" */
         name = u.net->has_id ? u.net->id : u.net->name;
     }
@@ -897,10 +954,12 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
             peer = net_hub_add_port(u.net->has_vlan ? u.net->vlan : 0, NULL);
         }
 
-        if (net_client_init_fun[opts->kind](opts, name, peer) < 0) {
-            /* TODO push error reporting into init() methods */
-            error_set(errp, QERR_DEVICE_INIT_FAILED,
-                      NetClientOptionsKind_lookup[opts->kind]);
+        if (net_client_init_fun[opts->kind](opts, name, peer, errp) < 0) {
+            /* FIXME drop when all init functions store an Error */
+            if (errp && !*errp) {
+                error_set(errp, QERR_DEVICE_INIT_FAILED,
+                          NetClientOptionsKind_lookup[opts->kind]);
+            }
             return -1;
         }
     }
diff --git a/net/netmap.c b/net/netmap.c
index 0c1772b..69300eb 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -446,8 +446,9 @@ static NetClientInfo net_netmap_info = {
  * ... -net netmap,ifname="..."
  */
 int net_init_netmap(const NetClientOptions *opts,
-        const char *name, NetClientState *peer)
+                    const char *name, NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     const NetdevNetmapOptions *netmap_opts = opts->netmap;
     NetClientState *nc;
     NetmapPriv me;
diff --git a/net/slirp.c b/net/slirp.c
index 9bbed74..0e15cf6 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -737,8 +737,9 @@ static const char **slirp_dnssearch(const StringList *dnsname)
 }
 
 int net_init_slirp(const NetClientOptions *opts, const char *name,
-                   NetClientState *peer)
+                   NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     struct slirp_config_str *config;
     char *vnet;
     int ret;
diff --git a/net/socket.c b/net/socket.c
index c30e03f..5a19aa1 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -693,8 +693,9 @@ static int net_socket_udp_init(NetClientState *peer,
 }
 
 int net_init_socket(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer)
+                    NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     Error *err = NULL;
     const NetdevSocketOptions *sock;
 
diff --git a/net/tap-aix.c b/net/tap-aix.c
index 804d164..18fdbf3 100644
--- a/net/tap-aix.c
+++ b/net/tap-aix.c
@@ -26,15 +26,14 @@
 #include <stdio.h>
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
-    fprintf(stderr, "no tap on AIX\n");
+    error_setg(errp, "no tap on AIX");
     return -1;
 }
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
-    return 0;
 }
 
 int tap_probe_vnet_hdr(int fd)
diff --git a/net/tap-bsd.c b/net/tap-bsd.c
index bf91bd0..5889920 100644
--- a/net/tap-bsd.c
+++ b/net/tap-bsd.c
@@ -35,7 +35,7 @@
 
 #ifndef __FreeBSD__
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
     int fd;
 #ifdef TAPGIFNAME
@@ -71,23 +71,19 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         }
     }
     if (fd < 0) {
-        error_report("warning: could not open %s (%s): no virtual network emulation",
-                   dname, strerror(errno));
+        error_setg_errno(errp, errno, "could not open %s", dname);
         return -1;
     }
 
 #ifdef TAPGIFNAME
     if (ioctl(fd, TAPGIFNAME, (void *)&ifr) < 0) {
-        fprintf(stderr, "warning: could not get tap name: %s\n",
-            strerror(errno));
+        error_setg_errno(errp, errno, "could not get tap name");
         return -1;
     }
     pstrcpy(ifname, ifname_size, ifr.ifr_name);
 #else
     if (fstat(fd, &s) < 0) {
-        fprintf(stderr,
-            "warning: could not stat /dev/tap: no virtual network emulation: %s\n",
-            strerror(errno));
+        error_setg_errno(errp, errno, "could not stat %s", dname);
         return -1;
     }
     dev = devname(s.st_rdev, S_IFCHR);
@@ -99,8 +95,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         *vnet_hdr = 0;
 
         if (vnet_hdr_required && !*vnet_hdr) {
-            error_report("vnet_hdr=1 requested, but no kernel "
-                         "support for IFF_VNET_HDR available");
+            error_setg(errp, "vnet_hdr=1 requested, but no kernel "
+                       "support for IFF_VNET_HDR available");
             close(fd);
             return -1;
         }
@@ -114,14 +110,14 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
 #define PATH_NET_TAP "/dev/tap"
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
     int fd, s, ret;
     struct ifreq ifr;
 
     TFR(fd = open(PATH_NET_TAP, O_RDWR));
     if (fd < 0) {
-        error_report("could not open %s: %s", PATH_NET_TAP, strerror(errno));
+        error_setg_errno(errp, errno, "could not open %s", PATH_NET_TAP);
         return -1;
     }
 
@@ -129,7 +125,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
 
     ret = ioctl(fd, TAPGIFNAME, (void *)&ifr);
     if (ret < 0) {
-        error_report("could not get tap interface name");
+        error_setg_errno(errp, errno, "could not get tap interface name");
         goto error;
     }
 
@@ -137,14 +133,15 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         /* User requested the interface to have a specific name */
         s = socket(AF_LOCAL, SOCK_DGRAM, 0);
         if (s < 0) {
-            error_report("could not open socket to set interface name");
+            error_setg_errno(errp, errno,
+                             "could not open socket to set interface name");
             goto error;
         }
         ifr.ifr_data = ifname;
         ret = ioctl(s, SIOCSIFNAME, (void *)&ifr);
         close(s);
         if (ret < 0) {
-            error_report("could not set tap interface name");
+            error_setg(errp, "could not set tap interface name");
             goto error;
         }
     } else {
@@ -156,14 +153,14 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         *vnet_hdr = 0;
 
         if (vnet_hdr_required && !*vnet_hdr) {
-            error_report("vnet_hdr=1 requested, but no kernel "
-                         "support for IFF_VNET_HDR available");
+            error_setg(errp, "vnet_hdr=1 requested, but no kernel "
+                       "support for IFF_VNET_HDR available");
             goto error;
         }
     }
     if (mq_required) {
-        error_report("mq_required requested, but not kernel support"
-                     "for IFF_MULTI_QUEUE available");
+        error_setg(errp, "mq_required requested, but no kernel support"
+                   " for IFF_MULTI_QUEUE available");
         goto error;
     }
 
@@ -176,9 +173,8 @@ error:
 }
 #endif /* __FreeBSD__ */
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
-    return 0;
 }
 
 int tap_probe_vnet_hdr(int fd)
diff --git a/net/tap-haiku.c b/net/tap-haiku.c
index e5ce436..d18590c 100644
--- a/net/tap-haiku.c
+++ b/net/tap-haiku.c
@@ -26,15 +26,14 @@
 #include <stdio.h>
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
-    fprintf(stderr, "no tap on Haiku\n");
+    error_setg(errp, "no tap on Haiku");
     return -1;
 }
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
-    return 0;
 }
 
 int tap_probe_vnet_hdr(int fd)
diff --git a/net/tap-linux.c b/net/tap-linux.c
index 812bf2d..6c3caef 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -37,7 +37,7 @@
 #define PATH_NET_TUN "/dev/net/tun"
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
     struct ifreq ifr;
     int fd, ret;
@@ -46,7 +46,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
 
     TFR(fd = open(PATH_NET_TUN, O_RDWR));
     if (fd < 0) {
-        error_report("could not open %s: %m", PATH_NET_TUN);
+        error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
         return -1;
     }
     memset(&ifr, 0, sizeof(ifr));
@@ -70,8 +70,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         }
 
         if (vnet_hdr_required && !*vnet_hdr) {
-            error_report("vnet_hdr=1 requested, but no kernel "
-                         "support for IFF_VNET_HDR available");
+            error_setg(errp, "vnet_hdr=1 requested, but no kernel "
+                       "support for IFF_VNET_HDR available");
             close(fd);
             return -1;
         }
@@ -86,8 +86,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
 
     if (mq_required) {
         if (!(features & IFF_MULTI_QUEUE)) {
-            error_report("multiqueue required, but no kernel "
-                         "support for IFF_MULTI_QUEUE available");
+            error_setg(errp, "multiqueue required, but no kernel "
+                       "support for IFF_MULTI_QUEUE available");
             close(fd);
             return -1;
         } else {
@@ -102,9 +102,11 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
     if (ret != 0) {
         if (ifname[0] != '\0') {
-            error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name);
+            error_setg_errno(errp, errno, "could not configure %s (%s)",
+                             PATH_NET_TUN, ifr.ifr_name);
         } else {
-            error_report("could not configure %s: %m", PATH_NET_TUN);
+            error_setg_errno(errp, errno, "could not configure %s",
+                             PATH_NET_TUN);
         }
         close(fd);
         return -1;
@@ -126,7 +128,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
  */
 #define TAP_DEFAULT_SNDBUF 0
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
     int sndbuf;
 
@@ -139,10 +141,8 @@ int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
     }
 
     if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
-        error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno));
-        return -1;
+        error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
     }
-    return 0;
 }
 
 int tap_probe_vnet_hdr(int fd)
diff --git a/net/tap-solaris.c b/net/tap-solaris.c
index 9c7278f..90b2fd1 100644
--- a/net/tap-solaris.c
+++ b/net/tap-solaris.c
@@ -36,7 +36,6 @@
 #include <netinet/udp.h>
 #include <netinet/tcp.h>
 #include <net/if.h>
-#include <syslog.h>
 #include <stropts.h>
 #include "qemu/error-report.h"
 
@@ -56,8 +55,10 @@ ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
  * Allocate TAP device, returns opened fd.
  * Stores dev name in the first arg(must be large enough).
  */
-static int tap_alloc(char *dev, size_t dev_size)
+static int tap_alloc(char *dev, size_t dev_size, Error **errp)
 {
+    /* FIXME leaks like a sieve on error paths */
+    /* FIXME suspicious: many errors are reported, then ignored */
     int tap_fd, if_fd, ppa = -1;
     static int ip_fd = 0;
     char *ptr;
@@ -83,14 +84,14 @@ static int tap_alloc(char *dev, size_t dev_size)
 
     TFR(ip_fd = open("/dev/udp", O_RDWR, 0));
     if (ip_fd < 0) {
-       syslog(LOG_ERR, "Can't open /dev/ip (actually /dev/udp)");
-       return -1;
+        error_setg(errp, "Can't open /dev/ip (actually /dev/udp)");
+        return -1;
     }
 
     TFR(tap_fd = open("/dev/tap", O_RDWR, 0));
     if (tap_fd < 0) {
-       syslog(LOG_ERR, "Can't open /dev/tap");
-       return -1;
+        error_setg(errp, "Can't open /dev/tap");
+        return -1;
     }
 
     /* Assign a new PPA and get its unit number. */
@@ -99,20 +100,20 @@ static int tap_alloc(char *dev, size_t dev_size)
     strioc_ppa.ic_len = sizeof(ppa);
     strioc_ppa.ic_dp = (char *)&ppa;
     if ((ppa = ioctl (tap_fd, I_STR, &strioc_ppa)) < 0)
-       syslog (LOG_ERR, "Can't assign new interface");
+        error_report("Can't assign new interface");
 
     TFR(if_fd = open("/dev/tap", O_RDWR, 0));
     if (if_fd < 0) {
-       syslog(LOG_ERR, "Can't open /dev/tap (2)");
-       return -1;
+        error_setg(errp, "Can't open /dev/tap (2)");
+        return -1;
     }
     if(ioctl(if_fd, I_PUSH, "ip") < 0){
-       syslog(LOG_ERR, "Can't push IP module");
-       return -1;
+        error_setg(errp, "Can't push IP module");
+        return -1;
     }
 
     if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) < 0)
-	syslog(LOG_ERR, "Can't get flags\n");
+        error_report("Can't get flags");
 
     snprintf (actual_name, 32, "tap%d", ppa);
     pstrcpy(ifr.lifr_name, sizeof(ifr.lifr_name), actual_name);
@@ -121,22 +122,22 @@ static int tap_alloc(char *dev, size_t dev_size)
     /* Assign ppa according to the unit number returned by tun device */
 
     if (ioctl (if_fd, SIOCSLIFNAME, &ifr) < 0)
-        syslog (LOG_ERR, "Can't set PPA %d", ppa);
+        error_report("Can't set PPA %d", ppa);
     if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) <0)
-        syslog (LOG_ERR, "Can't get flags\n");
+        error_report("Can't get flags");
     /* Push arp module to if_fd */
     if (ioctl (if_fd, I_PUSH, "arp") < 0)
-        syslog (LOG_ERR, "Can't push ARP module (2)");
+        error_report("Can't push ARP module (2)");
 
     /* Push arp module to ip_fd */
     if (ioctl (ip_fd, I_POP, NULL) < 0)
-        syslog (LOG_ERR, "I_POP failed\n");
+        error_report("I_POP failed");
     if (ioctl (ip_fd, I_PUSH, "arp") < 0)
-        syslog (LOG_ERR, "Can't push ARP module (3)\n");
+        error_report("Can't push ARP module (3)");
     /* Open arp_fd */
     TFR(arp_fd = open ("/dev/tap", O_RDWR, 0));
     if (arp_fd < 0)
-       syslog (LOG_ERR, "Can't open %s\n", "/dev/tap");
+        error_report("Can't open %s", "/dev/tap");
 
     /* Set ifname to arp */
     strioc_if.ic_cmd = SIOCSLIFNAME;
@@ -144,16 +145,16 @@ static int tap_alloc(char *dev, size_t dev_size)
     strioc_if.ic_len = sizeof(ifr);
     strioc_if.ic_dp = (char *)&ifr;
     if (ioctl(arp_fd, I_STR, &strioc_if) < 0){
-        syslog (LOG_ERR, "Can't set ifname to arp\n");
+        error_report("Can't set ifname to arp");
     }
 
     if((ip_muxid = ioctl(ip_fd, I_LINK, if_fd)) < 0){
-       syslog(LOG_ERR, "Can't link TAP device to IP");
-       return -1;
+        error_setg(errp, "Can't link TAP device to IP");
+        return -1;
     }
 
     if ((arp_muxid = ioctl (ip_fd, link_type, arp_fd)) < 0)
-        syslog (LOG_ERR, "Can't link TAP device to ARP");
+        error_report("Can't link TAP device to ARP");
 
     close (if_fd);
 
@@ -166,7 +167,7 @@ static int tap_alloc(char *dev, size_t dev_size)
     {
       ioctl (ip_fd, I_PUNLINK , arp_muxid);
       ioctl (ip_fd, I_PUNLINK, ip_muxid);
-      syslog (LOG_ERR, "Can't set multiplexor id");
+      error_report("Can't set multiplexor id");
     }
 
     snprintf(dev, dev_size, "tap%d", ppa);
@@ -174,13 +175,14 @@ static int tap_alloc(char *dev, size_t dev_size)
 }
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required)
+             int vnet_hdr_required, int mq_required, Error **errp)
 {
     char  dev[10]="";
     int fd;
-    if( (fd = tap_alloc(dev, sizeof(dev))) < 0 ){
-       fprintf(stderr, "Cannot allocate TAP device\n");
-       return -1;
+
+    fd = tap_alloc(dev, sizeof(dev), errp);
+    if (fd < 0) {
+        return -1;
     }
     pstrcpy(ifname, ifname_size, dev);
     if (*vnet_hdr) {
@@ -188,8 +190,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         *vnet_hdr = 0;
 
         if (vnet_hdr_required && !*vnet_hdr) {
-            error_report("vnet_hdr=1 requested, but no kernel "
-                         "support for IFF_VNET_HDR available");
+            error_setg(errp, "vnet_hdr=1 requested, but no kernel "
+                       "support for IFF_VNET_HDR available");
             close(fd);
             return -1;
         }
@@ -198,9 +200,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     return fd;
 }
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
-    return 0;
 }
 
 int tap_probe_vnet_hdr(int fd)
diff --git a/net/tap-win32.c b/net/tap-win32.c
index 8aee611..f6fc961 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -752,8 +752,9 @@ static int tap_win32_init(NetClientState *peer, const char *model,
 }
 
 int net_init_tap(const NetClientOptions *opts, const char *name,
-                 NetClientState *peer)
+                 NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     const NetdevTapOptions *tap;
 
     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_TAP);
diff --git a/net/tap.c b/net/tap.c
index 968df46..d1ca314 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -59,7 +59,8 @@ typedef struct TAPState {
     unsigned host_vnet_hdr_len;
 } TAPState;
 
-static int launch_script(const char *setup_script, const char *ifname, int fd);
+static void launch_script(const char *setup_script, const char *ifname,
+                          int fd, Error **errp);
 
 static int tap_can_send(void *opaque);
 static void tap_send(void *opaque);
@@ -288,6 +289,7 @@ static void tap_set_offload(NetClientState *nc, int csum, int tso4,
 static void tap_cleanup(NetClientState *nc)
 {
     TAPState *s = DO_UPCAST(TAPState, nc, nc);
+    Error *err = NULL;
 
     if (s->vhost_net) {
         vhost_net_cleanup(s->vhost_net);
@@ -296,8 +298,12 @@ static void tap_cleanup(NetClientState *nc)
 
     qemu_purge_queued_packets(nc);
 
-    if (s->down_script[0])
-        launch_script(s->down_script, s->down_script_arg, s->fd);
+    if (s->down_script[0]) {
+        launch_script(s->down_script, s->down_script_arg, s->fd, &err);
+        if (err) {
+            error_report_err(err);
+        }
+    }
 
     tap_read_poll(s, false);
     tap_write_poll(s, false);
@@ -368,7 +374,8 @@ static TAPState *net_tap_fd_init(NetClientState *peer,
     return s;
 }
 
-static int launch_script(const char *setup_script, const char *ifname, int fd)
+static void launch_script(const char *setup_script, const char *ifname,
+                          int fd, Error **errp)
 {
     int pid, status;
     char *args[3];
@@ -376,6 +383,11 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
 
     /* try to launch network script */
     pid = fork();
+    if (pid < 0) {
+        error_setg_errno(errp, errno, "could not launch network script %s",
+                         setup_script);
+        return;
+    }
     if (pid == 0) {
         int open_max = sysconf(_SC_OPEN_MAX), i;
 
@@ -390,17 +402,17 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
         *parg = NULL;
         execv(setup_script, args);
         _exit(1);
-    } else if (pid > 0) {
+    } else {
         while (waitpid(pid, &status, 0) != pid) {
             /* loop */
         }
 
         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
-            return 0;
+            return;
         }
+        error_setg(errp, "network script %s failed with status %d",
+                   setup_script, status);
     }
-    fprintf(stderr, "%s: could not launch network script\n", setup_script);
-    return -1;
 }
 
 static int recv_fd(int c)
@@ -437,7 +449,8 @@ static int recv_fd(int c)
     return len;
 }
 
-static int net_bridge_run_helper(const char *helper, const char *bridge)
+static int net_bridge_run_helper(const char *helper, const char *bridge,
+                                 Error **errp)
 {
     sigset_t oldmask, mask;
     int pid, status;
@@ -450,11 +463,16 @@ static int net_bridge_run_helper(const char *helper, const char *bridge)
     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 
     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
+        error_setg_errno(errp, errno, "socketpair() failed");
         return -1;
     }
 
     /* try to launch bridge helper */
     pid = fork();
+    if (pid < 0) {
+        error_setg_errno(errp, errno, "Can't fork bridge helper");
+        return -1;
+    }
     if (pid == 0) {
         int open_max = sysconf(_SC_OPEN_MAX), i;
         char fd_buf[6+10];
@@ -502,14 +520,16 @@ static int net_bridge_run_helper(const char *helper, const char *bridge)
         }
         _exit(1);
 
-    } else if (pid > 0) {
+    } else {
         int fd;
+        int saved_errno;
 
         close(sv[1]);
 
         do {
             fd = recv_fd(sv[0]);
         } while (fd == -1 && errno == EINTR);
+        saved_errno = errno;
 
         close(sv[0]);
 
@@ -518,24 +538,23 @@ static int net_bridge_run_helper(const char *helper, const char *bridge)
         }
         sigprocmask(SIG_SETMASK, &oldmask, NULL);
         if (fd < 0) {
-            fprintf(stderr, "failed to recv file descriptor\n");
+            error_setg_errno(errp, saved_errno,
+                             "failed to recv file descriptor");
             return -1;
         }
-
-        if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
-            return fd;
+        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+            error_setg(errp, "bridge helper failed");
+            return -1;
         }
+        return fd;
     }
-    fprintf(stderr, "failed to launch bridge helper\n");
-    return -1;
 }
 
 int net_init_bridge(const NetClientOptions *opts, const char *name,
-                    NetClientState *peer)
+                    NetClientState *peer, Error **errp)
 {
     const NetdevBridgeOptions *bridge;
     const char *helper, *br;
-
     TAPState *s;
     int fd, vnet_hdr;
 
@@ -545,20 +564,14 @@ int net_init_bridge(const NetClientOptions *opts, const char *name,
     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 
-    fd = net_bridge_run_helper(helper, br);
+    fd = net_bridge_run_helper(helper, br, errp);
     if (fd == -1) {
         return -1;
     }
 
     fcntl(fd, F_SETFL, O_NONBLOCK);
-
     vnet_hdr = tap_probe_vnet_hdr(fd);
-
     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
-    if (!s) {
-        close(fd);
-        return -1;
-    }
 
     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
              br);
@@ -568,8 +581,9 @@ int net_init_bridge(const NetClientOptions *opts, const char *name,
 
 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
                         const char *setup_script, char *ifname,
-                        size_t ifname_sz, int mq_required)
+                        size_t ifname_sz, int mq_required, Error **errp)
 {
+    Error *err = NULL;
     int fd, vnet_hdr_required;
 
     if (tap->has_vnet_hdr) {
@@ -581,17 +595,20 @@ static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
     }
 
     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
-                      mq_required));
+                      mq_required, errp));
     if (fd < 0) {
         return -1;
     }
 
     if (setup_script &&
         setup_script[0] != '\0' &&
-        strcmp(setup_script, "no") != 0 &&
-        launch_script(setup_script, ifname, fd)) {
-        close(fd);
-        return -1;
+        strcmp(setup_script, "no") != 0) {
+        launch_script(setup_script, ifname, fd, &err);
+        if (err) {
+            error_propagate(errp, err);
+            close(fd);
+            return -1;
+        }
     }
 
     return fd;
@@ -599,23 +616,20 @@ static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 
 #define MAX_TAP_QUEUES 1024
 
-static int net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
-                            const char *model, const char *name,
-                            const char *ifname, const char *script,
-                            const char *downscript, const char *vhostfdname,
-                            int vnet_hdr, int fd)
+static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
+                             const char *model, const char *name,
+                             const char *ifname, const char *script,
+                             const char *downscript, const char *vhostfdname,
+                             int vnet_hdr, int fd, Error **errp)
 {
     Error *err = NULL;
-    TAPState *s;
+    TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
     int vhostfd;
 
-    s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
-    if (!s) {
-        return -1;
-    }
-
-    if (tap_set_sndbuf(s->fd, tap) < 0) {
-        return -1;
+    tap_set_sndbuf(s->fd, tap, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
     }
 
     if (tap->has_fd || tap->has_fds) {
@@ -646,30 +660,28 @@ static int net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         if (tap->has_vhostfd || tap->has_vhostfds) {
             vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err);
             if (vhostfd == -1) {
-                error_report_err(err);
-                return -1;
+                error_propagate(errp, err);
+                return;
             }
         } else {
             vhostfd = open("/dev/vhost-net", O_RDWR);
             if (vhostfd < 0) {
-                error_report("tap: open vhost char device failed: %s",
-                           strerror(errno));
-                return -1;
+                error_setg_errno(errp, errno,
+                                 "tap: open vhost char device failed");
+                return;
             }
         }
         options.opaque = (void *)(uintptr_t)vhostfd;
 
         s->vhost_net = vhost_net_init(&options);
         if (!s->vhost_net) {
-            error_report("vhost-net requested but could not be initialized");
-            return -1;
+            error_setg(errp,
+                       "vhost-net requested but could not be initialized");
+            return;
         }
     } else if (tap->has_vhostfd || tap->has_vhostfds) {
-        error_report("vhostfd= is not valid without vhost");
-        return -1;
+        error_setg(errp, "vhostfd= is not valid without vhost");
     }
-
-    return 0;
 }
 
 static int get_fds(char *str, char *fds[], int max)
@@ -699,7 +711,7 @@ static int get_fds(char *str, char *fds[], int max)
 }
 
 int net_init_tap(const NetClientOptions *opts, const char *name,
-                 NetClientState *peer)
+                 NetClientState *peer, Error **errp)
 {
     const NetdevTapOptions *tap;
     int fd, vnet_hdr = 0, i = 0, queues;
@@ -718,7 +730,7 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
     /* QEMU vlans does not support multiqueue tap, in this case peer is set.
      * For -netdev, peer is always NULL. */
     if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
-        error_report("Multiqueue tap cannot be used with QEMU vlans");
+        error_setg(errp, "Multiqueue tap cannot be used with QEMU vlans");
         return -1;
     }
 
@@ -726,15 +738,15 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
             tap->has_fds || tap->has_vhostfds) {
-            error_report("ifname=, script=, downscript=, vnet_hdr=, "
-                         "helper=, queues=, fds=, and vhostfds= "
-                         "are invalid with fd=");
+            error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
+                       "helper=, queues=, fds=, and vhostfds= "
+                       "are invalid with fd=");
             return -1;
         }
 
         fd = monitor_fd_param(cur_mon, tap->fd, &err);
         if (fd == -1) {
-            error_report_err(err);
+            error_propagate(errp, err);
             return -1;
         }
 
@@ -742,9 +754,11 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
 
         vnet_hdr = tap_probe_vnet_hdr(fd);
 
-        if (net_init_tap_one(tap, peer, "tap", name, NULL,
-                             script, downscript,
-                             vhostfdname, vnet_hdr, fd)) {
+        net_init_tap_one(tap, peer, "tap", name, NULL,
+                         script, downscript,
+                         vhostfdname, vnet_hdr, fd, &err);
+        if (err) {
+            error_propagate(errp, err);
             return -1;
         }
     } else if (tap->has_fds) {
@@ -755,9 +769,9 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
             tap->has_vhostfd) {
-            error_report("ifname=, script=, downscript=, vnet_hdr=, "
-                         "helper=, queues=, and vhostfd= "
-                         "are invalid with fds=");
+            error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
+                       "helper=, queues=, and vhostfd= "
+                       "are invalid with fds=");
             return -1;
         }
 
@@ -765,8 +779,8 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
         if (tap->has_vhostfds) {
             nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
             if (nfds != nvhosts) {
-                error_report("The number of fds passed does not match the "
-                             "number of vhostfds passed");
+                error_setg(errp, "The number of fds passed does not match "
+                           "the number of vhostfds passed");
                 return -1;
             }
         }
@@ -774,7 +788,7 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
         for (i = 0; i < nfds; i++) {
             fd = monitor_fd_param(cur_mon, fds[i], &err);
             if (fd == -1) {
-                error_report_err(err);
+                error_propagate(errp, err);
                 return -1;
             }
 
@@ -783,26 +797,30 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
             if (i == 0) {
                 vnet_hdr = tap_probe_vnet_hdr(fd);
             } else if (vnet_hdr != tap_probe_vnet_hdr(fd)) {
-                error_report("vnet_hdr not consistent across given tap fds");
+                error_setg(errp,
+                           "vnet_hdr not consistent across given tap fds");
                 return -1;
             }
 
-            if (net_init_tap_one(tap, peer, "tap", name, ifname,
-                                 script, downscript,
-                                 tap->has_vhostfds ? vhost_fds[i] : NULL,
-                                 vnet_hdr, fd)) {
+            net_init_tap_one(tap, peer, "tap", name, ifname,
+                             script, downscript,
+                             tap->has_vhostfds ? vhost_fds[i] : NULL,
+                             vnet_hdr, fd, &err);
+            if (err) {
+                error_propagate(errp, err);
                 return -1;
             }
         }
     } else if (tap->has_helper) {
         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
             tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
-            error_report("ifname=, script=, downscript=, and vnet_hdr= "
-                         "queues=, and vhostfds= are invalid with helper=");
+            error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
+                       "queues=, and vhostfds= are invalid with helper=");
             return -1;
         }
 
-        fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE);
+        fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE,
+                                   errp);
         if (fd == -1) {
             return -1;
         }
@@ -810,15 +828,17 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
         fcntl(fd, F_SETFL, O_NONBLOCK);
         vnet_hdr = tap_probe_vnet_hdr(fd);
 
-        if (net_init_tap_one(tap, peer, "bridge", name, ifname,
-                             script, downscript, vhostfdname,
-                             vnet_hdr, fd)) {
+        net_init_tap_one(tap, peer, "bridge", name, ifname,
+                         script, downscript, vhostfdname,
+                         vnet_hdr, fd, &err);
+        if (err) {
+            error_propagate(errp, err);
             close(fd);
             return -1;
         }
     } else {
         if (tap->has_vhostfds) {
-            error_report("vhostfds= is invalid if fds= wasn't specified");
+            error_setg(errp, "vhostfds= is invalid if fds= wasn't specified");
             return -1;
         }
         script = tap->has_script ? tap->script : DEFAULT_NETWORK_SCRIPT;
@@ -833,23 +853,25 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
 
         for (i = 0; i < queues; i++) {
             fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
-                              ifname, sizeof ifname, queues > 1);
+                              ifname, sizeof ifname, queues > 1, errp);
             if (fd == -1) {
                 return -1;
             }
 
             if (queues > 1 && i == 0 && !tap->has_ifname) {
                 if (tap_fd_get_ifname(fd, ifname)) {
-                    error_report("Fail to get ifname");
+                    error_setg(errp, "Fail to get ifname");
                     close(fd);
                     return -1;
                 }
             }
 
-            if (net_init_tap_one(tap, peer, "tap", name, ifname,
-                                 i >= 1 ? "no" : script,
-                                 i >= 1 ? "no" : downscript,
-                                 vhostfdname, vnet_hdr, fd)) {
+            net_init_tap_one(tap, peer, "tap", name, ifname,
+                             i >= 1 ? "no" : script,
+                             i >= 1 ? "no" : downscript,
+                             vhostfdname, vnet_hdr, fd, &err);
+            if (err) {
+                error_propagate(errp, err);
                 close(fd);
                 return -1;
             }
diff --git a/net/tap_int.h b/net/tap_int.h
index 79afdf2..d12a409 100644
--- a/net/tap_int.h
+++ b/net/tap_int.h
@@ -30,11 +30,11 @@
 #include "qapi-types.h"
 
 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
-             int vnet_hdr_required, int mq_required);
+             int vnet_hdr_required, int mq_required, Error **errp);
 
 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen);
 
-int tap_set_sndbuf(int fd, const NetdevTapOptions *tap);
+void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp);
 int tap_probe_vnet_hdr(int fd);
 int tap_probe_vnet_hdr_len(int fd, int len);
 int tap_probe_has_ufo(int fd);
diff --git a/net/vde.c b/net/vde.c
index 2a619fb..dacaa64 100644
--- a/net/vde.c
+++ b/net/vde.c
@@ -110,8 +110,9 @@ static int net_vde_init(NetClientState *peer, const char *model,
 }
 
 int net_init_vde(const NetClientOptions *opts, const char *name,
-                 NetClientState *peer)
+                 NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     const NetdevVdeOptions *vde;
 
     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_VDE);
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 1d86a2b..11899c5 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -223,8 +223,9 @@ static int net_vhost_check_net(QemuOpts *opts, void *opaque)
 }
 
 int net_init_vhost_user(const NetClientOptions *opts, const char *name,
-                        NetClientState *peer)
+                        NetClientState *peer, Error **errp)
 {
+    /* FIXME error_setg(errp, ...) on failure */
     const NetdevVhostUserOptions *vhost_user_opts;
     CharDriverState *chr;
 
diff --git a/qemu-options.hx b/qemu-options.hx
index ec356f6..88d7661 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1449,25 +1449,25 @@ DEF("smb", HAS_ARG, QEMU_OPTION_smb, "", QEMU_ARCH_ALL)
 #endif
 #endif
 
-DEF("net", HAS_ARG, QEMU_OPTION_net,
-    "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
-    "                create a new Network Interface Card and connect it to VLAN 'n'\n"
+DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
 #ifdef CONFIG_SLIRP
-    "-net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=on|off]\n"
+    "-netdev user,id=str[,net=addr[/mask]][,host=addr][,restrict=on|off]\n"
     "         [,hostname=host][,dhcpstart=addr][,dns=addr][,dnssearch=domain][,tftp=dir]\n"
     "         [,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
 #ifndef _WIN32
                                              "[,smb=dir[,smbserver=addr]]\n"
 #endif
-    "                connect the user mode network stack to VLAN 'n', configure its\n"
-    "                DHCP server and enabled optional services\n"
+    "                configure a user mode network backend with ID 'str',\n"
+    "                its DHCP server and optional services\n"
 #endif
 #ifdef _WIN32
-    "-net tap[,vlan=n][,name=str],ifname=name\n"
-    "                connect the host TAP network interface to VLAN 'n'\n"
+    "-netdev tap,id=str,ifname=name\n"
+    "                configure a host TAP network backend with ID 'str'\n"
 #else
-    "-net tap[,vlan=n][,name=str][,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
-    "                connect the host TAP network interface to VLAN 'n'\n"
+    "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
+    "         [,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
+    "         [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
+    "                configure a host TAP network backend with ID 'str'\n"
     "                use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
     "                to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
     "                to deconfigure it\n"
@@ -1486,14 +1486,18 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
     "                use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
     "                use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
-    "-net bridge[,vlan=n][,name=str][,br=bridge][,helper=helper]\n"
-    "                connects a host TAP network interface to a host bridge device 'br'\n"
-    "                (default=" DEFAULT_BRIDGE_INTERFACE ") using the program 'helper'\n"
-    "                (default=" DEFAULT_BRIDGE_HELPER ")\n"
+    "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
+    "                configure a host TAP network backend with ID 'str' that is\n"
+    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
+    "                using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
 #endif
 #ifdef __linux__
-    "-net l2tpv3[,vlan=n][,name=str],src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6=on/off][,udp=on/off][,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]\n"
-    "                connect the VLAN to an Ethernet over L2TPv3 pseudowire\n"
+    "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
+    "         [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
+    "         [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
+    "         [,rxcookie=rxcookie][,offset=offset]\n"
+    "                configure a network backend with ID 'str' connected to\n"
+    "                an Ethernet over L2TPv3 pseudowire.\n"
     "                Linux kernel 3.3+ as well as most routers can talk\n"
     "                L2TPv3. This transport allows connecting a VM to a VM,\n"
     "                VM to a router and even VM to Host. It is a nearly-universal\n"
@@ -1514,32 +1518,41 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                use 'pincounter=on' to work around broken counter handling in peer\n"
     "                use 'offset=X' to add an extra offset between header and data\n"
 #endif
-    "-net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]\n"
-    "                connect the vlan 'n' to another VLAN using a socket connection\n"
-    "-net socket[,vlan=n][,name=str][,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
-    "                connect the vlan 'n' to multicast maddr and port\n"
+    "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
+    "                configure a network backend to connect to another network\n"
+    "                using a socket connection\n"
+    "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
+    "                configure a network backend to connect to a multicast maddr and port\n"
     "                use 'localaddr=addr' to specify the host address to send packets from\n"
-    "-net socket[,vlan=n][,name=str][,fd=h][,udp=host:port][,localaddr=host:port]\n"
-    "                connect the vlan 'n' to another VLAN using an UDP tunnel\n"
+    "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
+    "                configure a network backend to connect to another network\n"
+    "                using an UDP tunnel\n"
 #ifdef CONFIG_VDE
-    "-net vde[,vlan=n][,name=str][,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
-    "                connect the vlan 'n' to port 'n' of a vde switch running\n"
-    "                on host and listening for incoming connections on 'socketpath'.\n"
+    "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
+    "                configure a network backend to connect to port 'n' of a vde switch\n"
+    "                running on host and listening for incoming connections on 'socketpath'.\n"
     "                Use group 'groupname' and mode 'octalmode' to change default\n"
     "                ownership and permissions for communication port.\n"
 #endif
 #ifdef CONFIG_NETMAP
-    "-net netmap,ifname=name[,devname=nmname]\n"
+    "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
     "                attach to the existing netmap-enabled network interface 'name', or to a\n"
     "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
     "                netmap device, defaults to '/dev/netmap')\n"
 #endif
+    "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
+    "                configure a vhost-user network, backed by a chardev 'dev'\n"
+    "-netdev hubport,id=str,hubid=n\n"
+    "                configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL)
+DEF("net", HAS_ARG, QEMU_OPTION_net,
+    "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
+    "                old way to create a new NIC and connect it to VLAN 'n'\n"
+    "                (use the '-device devtype,netdev=str' option if possible instead)\n"
     "-net dump[,vlan=n][,file=f][,len=n]\n"
     "                dump traffic on vlan 'n' to file 'f' (max n bytes per packet)\n"
     "-net none       use it alone to have zero network devices. If no -net option\n"
-    "                is provided, the default is '-net nic -net user'\n", QEMU_ARCH_ALL)
-DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
-    "-netdev ["
+    "                is provided, the default is '-net nic -net user'\n"
+    "-net ["
 #ifdef CONFIG_SLIRP
     "user|"
 #endif
@@ -1551,9 +1564,9 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
 #ifdef CONFIG_NETMAP
     "netmap|"
 #endif
-    "vhost-user|"
-    "socket|"
-    "hubport],id=str[,option][,option][,...]\n", QEMU_ARCH_ALL)
+    "socket][,vlan=n][,option][,option][,...]\n"
+    "                old way to initialize a host network interface\n"
+    "                (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
 STEXI
 @item -net nic[,vlan=@var{n}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}]
 @findex -net