On 10/01/2018 15:32, Thomas Huth wrote: > QEMU can emulate hubs to connect NICs and netdevs. This is currently > primarily used for the mis-named 'vlan' feature of the networking > subsystem. Now the 'vlan' feature has been marked as deprecated, since > its name is rather confusing and the users often rather mis-configure > their network when trying to use it. But while the 'vlan' parameter > should be removed at one point in time, the basic idea of emulating > a hub in QEMU is still good: It's useful for bundling up the output of > multiple NICs into one single l2tp netdev for example. > > Now to be able to use the hubport feature without 'vlan's, there is one > missing piece: The possibility to connect a hubport to a netdev, too. > This patch adds this possibility by introducing a new "netdev=..." > parameter to the hubports. > > To bundle up the output of multiple NICs into one socket netdev, you can > now run QEMU with these parameters for example: > > qemu-system-ppc64 ... -netdev socket,id=s1,connect=:11122 \ > -netdev hubport,hubid=1,id=h1,netdev=s1 \ > -netdev hubport,hubid=1,id=h2 -device e1000,netdev=h2 \ > -netdev hubport,hubid=1,id=h3 -device virtio-net-pci,netdev=h3 > > For using the socket netdev, you have got to start another QEMU as the > receiving side first, for example with network dumping enabled: > > qemu-system-x86_64 -M isapc -netdev socket,id=s0,listen=:11122 \ > -device ne2k_isa,netdev=s0 \ > -object filter-dump,id=f1,netdev=s0,file=/tmp/dump.dat > > After the ppc64 guest tried to boot from both NICs, you can see in the > dump file (using Wireshark, for example), that the output of both NICs > (the e1000 and the virtio-net-pci) has been successfully transfered > via the socket netdev in this case. > > Suggested-by: Paolo Bonzini <pbonz...@redhat.com> > Signed-off-by: Thomas Huth <th...@redhat.com> > --- > See also the original discussion here for some more information: > https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg05650.html > > net/hub.c | 23 ++++++++++++++++++++++- > qapi/net.json | 4 +++- > qemu-options.hx | 8 +++++--- > 3 files changed, 30 insertions(+), 5 deletions(-) > > diff --git a/net/hub.c b/net/hub.c > index 14b4eec..0638729 100644 > --- a/net/hub.c > +++ b/net/hub.c > @@ -13,6 +13,7 @@ > */ > > #include "qemu/osdep.h" > +#include "qapi/error.h" > #include "monitor/monitor.h" > #include "net/net.h" > #include "clients.h" > @@ -286,12 +287,32 @@ int net_init_hubport(const Netdev *netdev, const char > *name, > NetClientState *peer, Error **errp) > { > const NetdevHubPortOptions *hubport; > + NetClientState *hubncs; > > assert(netdev->type == NET_CLIENT_DRIVER_HUBPORT); > assert(!peer); > hubport = &netdev->u.hubport; > > - net_hub_add_port(hubport->hubid, name); > + hubncs = net_hub_add_port(hubport->hubid, name); > + if (!hubncs) { > + error_setg(errp, "failed to add port to hub %i with id '%s'", > + hubport->hubid, name); > + return -1; > + } > + > + if (hubport->has_netdev) { > + NetClientState *hubpeer; > + > + hubpeer = qemu_find_netdev(hubport->netdev); > + if (!hubpeer) { > + error_setg(errp, "netdev '%s' not found", hubport->netdev); > + return -1; > + } > + assert(!hubncs->peer && !hubpeer->peer); > + hubncs->peer = hubpeer; > + hubpeer->peer = hubncs; > + } > + > return 0; > } > > diff --git a/qapi/net.json b/qapi/net.json > index 4beff5d..e41e046 100644 > --- a/qapi/net.json > +++ b/qapi/net.json > @@ -410,12 +410,14 @@ > # Connect two or more net clients through a software hub. > # > # @hubid: hub identifier number > +# @netdev: used to connect hub to a netdev instead of a device (since 2.12) > # > # Since: 1.2 > ## > { 'struct': 'NetdevHubPortOptions', > 'data': { > - 'hubid': 'int32' } } > + 'hubid': 'int32', > + '*netdev': 'str' } } > > ## > # @NetdevNetmapOptions: > diff --git a/qemu-options.hx b/qemu-options.hx > index 678181c..9ec4af7 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -2017,7 +2017,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, > #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" > + "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" > " configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL) > DEF("net", HAS_ARG, QEMU_OPTION_net, > "-net > nic[,vlan=n][,netdev=nd][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" > @@ -2445,13 +2445,15 @@ vde_switch -F -sock /tmp/myswitch > qemu-system-i386 linux.img -net nic -net vde,sock=/tmp/myswitch > @end example > > -@item -netdev hubport,id=@var{id},hubid=@var{hubid} > +@item -netdev hubport,id=@var{id},hubid=@var{hubid}[,netdev=@var{nd}] > > Create a hub port on QEMU "vlan" @var{hubid}. > > The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a > single > netdev. @code{-net} and @code{-device} with parameter @option{vlan} create > the > -required hub automatically. > +required hub automatically. Alternatively, you can also connect the hubport > +to another netdev with ID @var{nd} by using the @option{netdev=@var{nd}} > +option. > > @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n] > >
Thank you very much! What is the next step for deprecating vlans? I guess 1) removing the vlan property from DEFINE_NIC_PROPERTIES 2) removing the vlan property from -net, defaulting to vlan 0 3) only allow exactly two -net options, one for the backend (creating a netdev) and one from the front-end (filling in nd_table) ? Thanks, Paolo
