Re: [Qemu-devel] [PATCH] Add -netdev to man page

[Miroslav Rezanina]

----- Original Message -----
> From: "Markus Armbruster" <address@hidden>
> To: "Miroslav Rezanina" <address@hidden>
> Cc: address@hidden
> Sent: Thursday, March 1, 2012 4:50:35 PM
> Subject: Re: [Qemu-devel] [PATCH] Add -netdev to man page
> 
> Miroslav Rezanina <address@hidden> writes:
> 
> > There's missing -netdev description in the man page for qemu. As
> > this is
> > recommended way to create network backend, lack of documentation
> > can discourage
> > its usage.
> 
> Very much appreciated!
> 
> > -net option is preserved but marked as obsolete way.
> >
> > Signed-off-by: Miroslav Rezanina <address@hidden>
> >
> > Patch:
> > -----
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index b129996..a1d61b6 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -1292,6 +1292,268 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
> >  #endif
> >      "socket],id=str[,option][,option][,...]\n", QEMU_ARCH_ALL)
> >  STEXI
> > address@hidden -netdev
> > user|tap|vde|socket,address@hidden,option][,option][,...]
> > +
> > +Create a new network backend to the guest. The backend's
> > @option{id} can be used with
> 
> Suggest to drop "to the guest".
> 
ok.

> > +the @option{-device} option to connect a backend with a device,
> > +e.g.
> > +
> > address@hidden
> > +-netdev user,id=mynet -device e1000,netdev=mynet
> > address@hidden example
> > +
> > +You can use following types of backend:
> > +
> > address@hidden @option
> > +
> > address@hidden -netdev user
> > +
> > +User networking is default network backend. This backend does not
> > require root
> > +priviledges, does not allow ICMP trafic and host is not directly
> > accessible
> > +from the host or the external network.
> 
> privileges
> 
> traffic
> 
> Suggest you use a spell checker :)
> 
> Comma after "traffic", please.
> 
> Err, "host is not directly accessible from the host"...  Do you mean
> "guest is not"?
> 
> > +Valid options are:
> > +
> > address@hidden @option
> > +
> > address@hidden restrict=y|yes|n|no
> 
> For -net, this is documented as restrict=on|off.  All these values
> are
> actually recognized.  I find that somewhat baroque, and don't
> particularly care which ones you document :)
>

I will go on|off way even if yes|no is possible. No need to use special
handling.
 
> > +If this options is enabled, the guest will be isolated, i.e. it
> > will not be
> 
> option
> 
> > +able to contact the host and no guest IP packets will be routed
> > over the host
> > +to the outside. This option does not affect explicitly set
> > forwarding rules.
> > +
> > address@hidden address@hidden/@var{mask}]
> > +Set the IP network address the guest will see. Optionally specify
> > the netmask,
> > +either in the form a.b.c.d or as number of valid top-most bits.
> > Default is
> > +10.0.2.0/8.
> 
> Documentation of -net has /24 here.  One of them might be wrong (I
> didn't check).
> 

You're right. I worked on both RHEL and upstream man page in paralel and
there's different text in both version. Correct value is /24.

> > +
> > address@hidden address@hidden
> > +Specify the guest-visible address of the host. Default is the 2nd
> > IP in the
> > +guest network, i.e. x.x.x.2.
> > +
> > address@hidden address@hidden
> > +Specifies the client hostname reported by the builtin DHCP server.
> > +
> > address@hidden address@hidden
> > +Specify the first of the 16 IPs the built-in DHCP server can
> > assign. Default
> > +is the 16th to 31st IP in the guest network, i.e. x.x.x.16 to
> > x.x.x.31.
> 
> Documentation of -net has 15th here.  One of them might be wrong (I
> didn't check).

Yes, 15 is correct start but I'm not sure with end value -> is 16 IP used
so last address is x.x.x.30 or is x.x.x.31 really last address?

> 
> > address@hidden address@hidden
> > +Specify the guest-visible address of the virtual nameserver. The
> > address must
> > +be different from the host address. Default is the 3rd IP in the
> > guest network,
> > +i.e. x.x.x.3.
> > +
> > address@hidden address@hidden
> > +When using the user mode network stack, activate a built-in TFTP
> > +server. The files in @var{dir} will be exposed as the root of a
> > TFTP server.
> > +The TFTP client on the guest must be configured in binary mode
> > (use the command
> > address@hidden of the Unix TFTP client).
> > +
> > address@hidden address@hidden
> > +When using the user mode network stack, broadcast @var{file} as
> > the BOOTP
> > +filename. In conjunction with @option{tftp}, this can be used to
> > network boot
> > +a guest from a local directory.
> > +
> > +Example (using pxelinux):
> > address@hidden
> > +qemu -hda linux.img -boot n -netdev
> > user,id=netid,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
> > address@hidden example
> > +
> > address@hidden address@hidden,address@hidden
> > +When using the user mode network stack, activate a built-in SMB
> > +server so that Windows OSes can access to the host files in
> > @address@hidden
> > +transparently. The IP address of the SMB server can be set to
> > @var{addr}. By
> > +default the 4th IP in the guest network is used, i.e. x.x.x.4.
> > +
> > +In the guest Windows OS, the line:
> > address@hidden
> > +10.0.2.4 smbserver
> > address@hidden example
> > +must be added in the file @file{C:\WINDOWS\LMHOSTS} (for windows
> > 9x/Me)
> > +or @file{C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS} (Windows NT/2000).
> > +
> > +Then @address@hidden can be accessed in @file{\\smbserver\qemu}.
> > +
> > +Note that a SAMBA server must be installed on the host OS in
> > address@hidden/usr/sbin/smbd}. QEMU was tested successfully with smbd
> > versions from
> > +Red Hat 9, Fedora Core 3 and OpenSUSE 11.x.
> > +
> > address@hidden
> > hostfwd=[tcp|udp]:address@hidden:@address@hidden:@var{guestport}
> > +Redirect incoming TCP or UDP connections to the host port
> > @var{hostport} to
> > +the guest IP address @var{guestaddr} on guest port
> > @var{guestport}. If
> > address@hidden is not specified, its value is x.x.x.15 (default
> > first address
> > +given by the built-in DHCP server). By specifying @var{hostaddr},
> > the rule can
> > +be bound to a specific host interface. If no connection type is
> > set, TCP is
> > +used. This option can be given multiple times.
> > +
> > +For example, to redirect host X11 connection from screen 1 to
> > guest
> > +screen 0, use the following:
> > +
> > address@hidden
> > +# on the host
> > +qemu -netdev user,id=netid,hostfwd=tcp:127.0.0.1:6001-:6000 [...]
> > +# this host xterm should open in the guest X11 server
> > +xterm -display :1
> > address@hidden example
> > +
> > +To redirect telnet connections from host port 5555 to telnet port
> > on
> > +the guest, use the following:
> > +
> > address@hidden
> > +# on the host
> > +qemu -netdev user,id=netid,hostfwd=tcp:5555::23 [...]
> > +telnet localhost 5555
> > address@hidden example
> > +
> > +Then when you use on the host @code{telnet localhost 5555}, you
> > +connect to the guest telnet server.
> > +
> > address@hidden guestfwd=[tcp]:@var{server}:@address@hidden
> > +Forward guest TCP connections to the IP address @var{server} on
> > port @var{port}
> > +to the character device @var{dev}. This option can be given
> > multiple times.
> > +
> > address@hidden table
> > +
> > address@hidden -netdev tap
> > +
> > +The tap networking backend makes use of a tap networking device in
> > the host.
> > +It offers very good performance and can be configured to create
> > virtually
> > +any type of network topology. It requires configuration of that
> > network
> > +topology in the host and invoking QEMU as root unless the tap
> > device has been
> > +preconfigured to be owned by the user invoking qemu, or the
> > @option{f}d option is used
> 
> @option{fd}
> 
> Since you're discussing non-root tap setup, perhaps point to the
> helper
> option as well.
> 

Yeap, worth adding note.

> > +
> > +Valid options are:
> > +
> > address@hidden @option
> > +
> > address@hidden address@hidden
> > +Name of host tap device to be used by qemu.
> > +
> > address@hidden address@hidden
> > +File descriptor of an already opened tap.
> > +
> > address@hidden address@hidden
> > +Network script used to configure device.
> > +
> > address@hidden address@hidden
> > +Network script used to deconfigure device.
> > +
> > address@hidden address@hidden
> > +Limit for send buffer.
> > +
> > address@hidden vnet_hdr=on|off]
> > +Enable the IFF_VNET_HDR flag on the tap interface.
> > +
> > address@hidden vhost=[on|off]
> > +Enable vhost-net network accelerator.
> > +
> > address@hidden address@hidden
> > +File descriptor of an already opened vhost-net device.
> > +
> > address@hidden vhostforce=[on|off]
> > +Force 'vhost=on' for non-MSIX virtio guests.
> > +
> > address@hidden address@hidden
> > +If running QEMU as an unprivileged user, use the network helper
> > address@hidden to configure the TAP interface. The default network
> > +helper executable is @file{/usr/local/libexec/qemu-bridge-helper}.
> 
> Should this be #ifdef CONFIG_NET_BRIDGE?
> 

As wrote before, this should be in ifdef even if it has no practical effect.

> > +
> > address@hidden table
> > +ETEXI
> > +#ifdef CONFIG_VDE
> > +STEXI
> > address@hidden -netdev vde
> > +
> > +Virtual Distributed Ethernet infrastructure is used. Unless you
> > specifically
> > +know that you want to use VDE, it is probably not the best backend
> > to use. This option
> > +is only available if QEMU has been compiled with vde support
> > enabled.
> > +
> > +Valid options are:
> > +
> > address@hidden @option
> > +
> > address@hidden address@hidden
> > +
> > +Path to the socket used for backend.
> > +
> > address@hidden address@hidden
> > +
> > +Port number.
> > +
> > address@hidden address@hidden
> > +
> > +Owner group for the used socket.
> > +
> > address@hidden address@hidden
> > +
> > +File permissions of used socket.
> > +
> > address@hidden table
> > +
> > +ETEXI
> > +#endif
> > +STEXI
> > +
> > address@hidden -netdev socket
> > +
> > +The socket networking backend allow you to create a network of
> > guests that can
> > +see each other. It's primarily useful in extending the network
> > created by slirp
> > +to multiple virtual machines.
> > +
> > +One of following options has to be specified:
> > +
> > address@hidden @option
> > +
> > address@hidden fd @var{descriptor}
> > +Qemu uses an already opened socket with file descriptor
> > @var{descriptor}
> > +
> > address@hidden listen address@hidden:@var{port}
> > +Specify port, and optionaly hostname, qemu will listen on.
> > +
> > address@hidden connect address@hidden:@var{port}
> > +Qemu connects to specified port and, optionaly, hostname.
> > +
> > address@hidden mcast @var{addr}
> > +Qemu uses UDP multicast address @var{addr}.
> > +
> > address@hidden udp @var{addr}:@var{port}
> > +Qemu uses UDP unicast address and port.
> > +
> > address@hidden table
> > +
> > +Option @address@hidden:@var{port} can be used for
> > @option{mcast}
> > +and has to be used for @option{udp} option. It specifiy source
> > address and port
> > +for udp packets.
> > +
> > +ETEXI
> > +#ifdef CONFIG_NET_BRIDGE
> > +STEXI
> > +
> > address@hidden -netdev
> > bridge,address@hidden,address@hidden,address@hidden
> > +Connect a host TAP network interface to a host bridge device. This
> > option is
> > +only available if QEMU has been compiled with net brdige support
> > enabled.
> 
> bridge
> 
> > +
> > +Valid options are:
> > +
> > address@hidden @option
> > +
> > address@hidden address@hidden
> > +Specify bridge TAP interface should be attached. Default value is
> > @file{br0}.
> > +
> > address@hidden address@hidden
> > +Network helper used to configure TAP inteface. Default helper is
> > address@hidden/usr/local/libexec/qemu-bridge-helper}.
> > +
> > address@hidden table
> > +ETEXI
> > +#endif
> > +STEXI
> > address@hidden table
> > address@hidden table
> > +
> > +Following options for backend creation are obsolete but still
> > working:
> > +
> > address@hidden @option
> > +
> >  @item -net
> >  nic[,address@hidden,address@hidden,address@hidden
> >  [,address@hidden,address@hidden,address@hidden
> >  @findex -net
> >  Create a new Network Interface Card and connect it to VLAN @var{n}
> >  (@var{n}
> 


New version to be sent soon.

Mirek