For qemu and upstream DPDK, support is present for the VIRTIO_NET_F_STATUS capability, and as such should not experience the "UNKNOWN" operstate issue; jvosburgh checked qemu and don't see this issue when running it, but haven't set up DPDK to verify it's behavior.
The opencontrail vrouter source code does not support VIRTIO_NET_F_STATUS, which dovetails with the prior analysis that suggests that this lack of support would lead to the operstate UNKNOWN. jvosburgh also examined the virtio specification itself. It indicates that if VIRTIO_NET_F_STATUS is not available, the "link should be assumed active." ** Tags added: sts -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1761534 Title: "ip a" command on a guest VM shows UNKNOWN status Status in linux package in Ubuntu: In Progress Status in linux source package in Xenial: In Progress Status in linux source package in Artful: In Progress Status in linux source package in Bionic: In Progress Bug description: It has been brought to my attention the following : ------------------------------------------------ Environment: The guest VM is using a canonical ubuntu image, and the eth0 is a virtio-net adaptor, running on DPDK. Background: "ip a" command relies on the operstate variable of the net_device structure maintained by the kernel. This is based on the operational state as defined in the IF MIB (RFC 2863). Device drivers are expected to update this member. But many older drivers don’t seem to be using this. So in general, IF_OPER_UP and IF_OPER_UNKNOWN are treated as equal, in some sense, to maintain backward compatibility. Even if we look at https://elixir.free- electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L3468, the function to check if interface is up, is written as follows, which says that OPER_UNKNOWN is not something to be alarmed about, and just reflective of a state that some drivers don’t care to update about. static inline bool netif_oper_up(const struct net_device *dev) { return (dev->operstate == IF_OPER_UP || dev->operstate == IF_OPER_UNKNOWN /* backward compat */); } Code Ref: 1. https://elixir.free-electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L1739 2. https://elixir.free-electrons.com/linux/v4.15-rc2/source/include/linux/netdevice.h#L3468 3. https://www.kernel.org/doc/Documentation/networking/operstates.txt Now, for traditional kernel mode network adapter drivers, this state is supposed to be manipulated by the driver. And we can safely assume that most current kernel model drivers do keep this updated. ------------------------------------------------ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1761534/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
