[Qemu-devel] [PATCH v2] qemu-options: add documentation for using UDP unicast network backend.

[Victor Kaplansky <victork@redhat.com>]

For the long time QEMU has support for UDP unicast network
backend added by commit 0e0e7facc775e9, but manual was missing
description and usage examples.

Changes from v1:

    Address comments by Michael S. Tsirkin:
      - remove superfluous empty lines.
      - place the note about two QEMU instances after the example.
      - English and others cleanups.

Signed-off-by: Victor Kaplansky <victork@redhat.com>
---
 qemu-options.hx | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/qemu-options.hx b/qemu-options.hx
index 2485b94..6bdb884 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1907,6 +1907,28 @@ qemu-system-i386 linux.img \
                  -net socket,mcast=239.192.168.1:1102,localaddr=1.2.3.4
 @end example
 
+@item -netdev socket,id=@var{id}[,fd=@var{h}][,udp=@var{rhost}:@var{rport}[,localaddr=@var{lhost}:@var{lport}]]
+@itemx -net socket[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,udp=@var{rhost}:@var{rport}[,localaddr=@var{rhost}:@var{lport}]]
+
+Connect a VLAN @var{n} to a remote VLAN in another QEMU virtual
+machine using a UDP tunnel. Use lhost:lport as the local host and
+port, rhost:rport as the remote host and port of the tunnel.  Use
+@option{fd=h} to specify an already opened UDP socket.
+
+Example:
+@example
+# launch one QEMU instance
+qemu-system-i386 linux.img \
+                 -device virtio-net-pci,netdev=net0 \
+                 -netdev socket,id=net0,udp=localhost:4444,localaddr=localhost:5555
+# launch a second QEMU instance sharing the network with the first one
+qemu-system-i386 linux.img \
+                 -device virtio-net-pci,netdev=net0 \
+                 -netdev socket,id=net0,udp=localhost:5555,localaddr=localhost:4444
+
+NOTE: The two QEMU instances can be running on different hosts.
+@end example
+
 @item -netdev l2tpv3,id=@var{id},src=@var{srcaddr},dst=@var{dstaddr}[,srcport=@var{srcport}][,dstport=@var{dstport}],txsession=@var{txsession}[,rxsession=@var{rxsession}][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=@var{txcookie}][,rxcookie=@var{rxcookie}][,offset=@var{offset}]
 @itemx -net l2tpv3[,vlan=@var{n}][,name=@var{name}],src=@var{srcaddr},dst=@var{dstaddr}[,srcport=@var{srcport}][,dstport=@var{dstport}],txsession=@var{txsession}[,rxsession=@var{rxsession}][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=@var{txcookie}][,rxcookie=@var{rxcookie}][,offset=@var{offset}]
 Connect VLAN @var{n} to L2TPv3 pseudowire. L2TPv3 (RFC3391) is a popular
-- 
--Victor