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VIO(4) Device Drivers Manual VIO(4)

vioVirtIO network device

vio* at virtio? flags 0x00

The vio driver provides support for the virtio(4) network interface provided by bhyve, KVM, QEMU, and VirtualBox.

Setting the bit 0x2 in the flags disables the RingEventIndex feature. This can be tried as a workaround for possible bugs in host implementations of vio at the cost of slightly reduced performance.

Setting the bit 0x100 in the flags forces the interface to be always in promiscuous mode. This can be used as a workaround for a bug in QEMU before version 1.7.2 that prevents packets with a VLAN tag from being sent to the guest.

intro(4), virtio(4)

The vio driver first appeared in OpenBSD 5.3.

The vio driver was ported to OpenBSD and improved by Stefan Fritsch <>. It is based on the NetBSD vioif driver by Minoura Makoto.

September 24, 2015 OpenBSD-6.1