'-net socket,mcast=' option support (initial patch by Juan Jose Ciarlante)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1710 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 36 insertions, 2 deletions

diff --git a/qemu-doc.texi b/qemu-doc.texi
index 7ec41f5..f970b2a 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -282,8 +282,8 @@ Connect the VLAN @var{n} to a remote VLAN in another QEMU virtual
 machine using a TCP socket connection. If @option{listen} is
 specified, QEMU waits for incoming connections on @var{port}
 (@var{host} is optional). @option{connect} is used to connect to
-another QEMU instance using the @option{listen} option.  @option{fd=h}
-specifies an already opened socket.
+another QEMU instance using the @option{listen} option. @option{fd=h}
+specifies an already opened TCP socket.
 
 Example:
 @example
@@ -293,6 +293,40 @@ qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,listen=:1234
 qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,connect=127.0.0.1:1234
 @end example
 
+@item -net socket[,vlan=n][,fd=h][,mcast=maddr:port]
+
+Create a VLAN @var{n} shared with another QEMU virtual
+machines using a UDP multicast socket, effectively making a bus for 
+every QEMU with same multicast address @var{maddr} and @var{port}.
+NOTES:
+@enumerate
+@item 
+Several QEMU can be running on different hosts and share same bus (assuming 
+correct multicast setup for these hosts).
+@item
+mcast support is compatible with User Mode Linux (argument @option{eth@var{N}=mcast}), see
+@url{http://user-mode-linux.sf.net}.
+@item Use @option{fd=h} to specify an already opened UDP multicast socket.
+@end enumerate
+
+Example:
+@example
+# launch one QEMU instance
+qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=230.0.0.1:1234
+# launch another QEMU instance on same "bus"
+qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,mcast=230.0.0.1:1234
+# launch yet another QEMU instance on same "bus"
+qemu linux.img -net nic,macaddr=52:54:00:12:34:58 -net socket,mcast=230.0.0.1:1234
+@end example
+
+Example (User Mode Linux compat.):
+@example
+# launch QEMU instance (note mcast address selected is UML's default)
+qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=239.192.168.1:1102
+# launch UML
+/path/to/linux ubd0=/path/to/root_fs eth0=mcast
+@end example
+
 @item -net none
 Indicate that no network devices should be configured. It is used to
 override the default configuration which is activated if no