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On 08/25/2016 05:42 AM, Vasiliy Tolstov
wrote:
25 Авг 2016 г. 12:34 пользователь Vasiliy Tolstov
<v.tolstov@xxxxxxxxx>
написал:
>
> 25 Авг 2016 г. 8:58 пользователь "Laine Stump" <laine@xxxxxxxxx>
написал:
> >
> > The linkstate setting of an <interface> is only
meant to change the
> > online status reported to the guest system by the
emulated network
> > device driver in qemu,
>
I need to set host side status of interface. Without this live
migration with dinamic routing software (ospf with quagga or
bird) bring packet drops. Because on dest interface in up state
and kernel try to forward packets to it, but guest CPU is not
running.
That shouldn't be a problem, since the IPInfo isn't added to the tap
device until immediately before the guest CPU is started on the
destination (that's the purpose of qemuInterfaceStartDevice()).
Also host side status needed for easy blackhole
traffic to guest ip.
Is this something you need to do while the guest is already running?
If not, then I think we don't need anything extra.
May be create inside the source link state attribute
for host side link status? So it consistent with ip and route
elements?
If necessary, that might be the right solution, although I still
think it's better to not set the tap device offline, in case it's
connected to a bridge - we wouldn't want to trigger an STP forward
delay. Maybe just delete (and later re-add) the IPInfo would be less
disruptive? (Or it might be *more* disruptive, we'd have to try
both).
>
> > but when support for auto-creating tap devices
> > for <interface type='ethernet'> was added in
commit 9717d6, a chunk of
> > code was also added to qemuDomainChangeNetLinkState()
that sets the
> > online status of the tap device (i.e. the *host* side
of the
> > interface) for type='ethernet'. This was never done
for tap devices
> > used in type='bridge' or type='network' interfaces,
nor was it done in
> > the past for tap devices created by external scripts
for
> > type='ethernet', so we shouldn't be doing it now.
> >
> > This patch removes the bit of code in
qemuDomainChangeNetLinkState()
> > that modifies online status of the tap device.
> > ---
> > src/qemu/qemu_hotplug.c | 15 ---------------
> > 1 file changed, 15 deletions(-)
> >
> > diff --git a/src/qemu/qemu_hotplug.c
b/src/qemu/qemu_hotplug.c
> > index 00e4a75..5300bc1 100644
> > --- a/src/qemu/qemu_hotplug.c
> > +++ b/src/qemu/qemu_hotplug.c
> > @@ -2324,21 +2324,6 @@ int
qemuDomainChangeNetLinkState(virQEMUDriverPtr driver,
> > if (ret < 0)
> > goto cleanup;
> >
> > - if (virDomainNetGetActualType(dev) ==
VIR_DOMAIN_NET_TYPE_ETHERNET) {
> > - switch (linkstate) {
> > - case
VIR_DOMAIN_NET_INTERFACE_LINK_STATE_UP:
> > - case
VIR_DOMAIN_NET_INTERFACE_LINK_STATE_DEFAULT:
> > - if ((ret =
virNetDevSetOnline(dev->ifname, true)) < 0)
> > - goto cleanup;
> > - break;
> > -
> > - case
VIR_DOMAIN_NET_INTERFACE_LINK_STATE_DOWN:
> > - if ((ret =
virNetDevSetOnline(dev->ifname, false)) < 0)
> > - goto cleanup;
> > - break;
> > - }
> > - }
> > -
> > /* modify the device configuration */
> > dev->linkstate = linkstate;
> >
> > --
> > 2.7.4
> >
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