commit 547203ead4327b353c25753a3ebb0acdc0ed2cf5
author Thomas Huth <thuth@redhat.com> Wed Feb 21 11:18:31 2018 +0100
committer Jason Wang <jasowang@redhat.com> Mon Mar 05 10:30:14 2018 +0800
tree bb7cdab82f732d0a14ef531dc9c4b93cdf8abe3c
parent 34f708b0b6bef9ac1e371879a47df5b5fb95726f

net: List available netdevs with "-netdev help"

Other options like "-chardev" or "-device" feature a nice help text
with the available devices when being called with "help" or "?".
Since it is quite useful, especially if you want to see which network
backends have been compiled into the QEMU binary, let's provide such
a help text for "-netdev", too.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/net.c

diff --git a/net/net.c b/net/net.c
index e213a61..cf07e15 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1086,6 +1086,38 @@
     return 0;
 }
 
+static void show_netdevs(void)
+{
+    int idx;
+    const char *available_netdevs[] = {
+        "socket",
+        "hubport",
+        "tap",
+#ifdef CONFIG_SLIRP
+        "user",
+#endif
+#ifdef CONFIG_L2TPV3
+        "l2tpv3",
+#endif
+#ifdef CONFIG_VDE
+        "vde",
+#endif
+#ifdef CONFIG_NET_BRIDGE
+        "bridge",
+#endif
+#ifdef CONFIG_NETMAP
+        "netmap",
+#endif
+#ifdef CONFIG_POSIX
+        "vhost-user",
+#endif
+    };
+
+    printf("Available netdev backend types:\n");
+    for (idx = 0; idx < ARRAY_SIZE(available_netdevs); idx++) {
+        puts(available_netdevs[idx]);
+    }
+}
 
 int net_client_init(QemuOpts *opts, bool is_netdev, Error **errp)
 {
@@ -1094,7 +1126,10 @@
     int ret = -1;
     Visitor *v = opts_visitor_new(opts);
 
-    {
+    if (is_netdev && is_help_option(qemu_opt_get(opts, "type"))) {
+        show_netdevs();
+        exit(0);
+    } else {
         /* Parse convenience option format ip6-net=fec0::0[/64] */
         const char *ip6_net = qemu_opt_get(opts, "ipv6-net");