> > > > On Wed, Jun 26, 2024 at 09:05:05AM +0000, Konstantin Taranov wrote: > > > > > > > When mc->ports[0] is not slave, use it in the set_netdev. > > > > > > > When mana is used in netvsc, the stored net devices in mana > > > > > > > are slaves and GIDs should be taken from their master devices. > > > > > > > In the baremetal case, the mc->ports devices will not be slaves. > > > > > > > > > > > > I wonder, why do you have "... | IFF_SLAVE" in > > > > > > __netvsc_vf_setup() in a first place? Isn't IFF_SLAVE is supposed to > be set by bond driver? > > > > > > > > > > > > > > > > I guess it is just a valid use of the IFF_SLAVE bit. In the bond > > > > > case it is also set as a BOND netdev. The IFF_SLAVE helps to show > users that another master > > > > > netdev should be used for networking. But I am not an expert in > netvsc. > > > > > > > > The thing is that netvsc is virtual device like many others, but > > > > it is the only one who uses IFF_SLAVE bit. The comment around that > > > > bit says "slave of a load balancer.", which is not the case > > > > according to the Hyper-V documentation. > > > > > > > > You will need to get Ack from netdev maintainers to rely on > > > > IFF_SLAVE bit in the way you are relying on it now. > > > > > > This is used to tell userspace tools to not interact directly with the device. > > > For example, it is used when VF is connected to netvsc device. > > > It prevents things like IPv6 local address, and Network Manager won't > modify device. > > > > You described how hyper-v uses it, but I'm interested to get > > acknowledgment that it is a valid use case for IFF_SLAVE, despite sentence > written in the comment. > > There is no documented semantics around any of the IF flags, only historical > precedent used by bond, team and bridge drivers. Initially Hyper-V VF used > bonding but it was impossibly difficult to make this work across all versions of > Linux, so transparent VF support was added instead. Ideally, the VF device > could be hidden from userspace but that required more kernel modifications > than would be accepted. Thanks Stephen for the explanation! I am also CCing Haiyang, who maintains Hyper-V netvsc.
