---
name: "vio"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/vio"
---

# vio(4)

VirtIO network device

## NAME

**vio** – VirtIO network device

## SYNOPSIS

**vio\* at virtio? flags 0x00**

## DESCRIPTION

The **vio** driver provides support for the [virtio(4)](/virtio/4.md) network interface provided by bhyve, KVM, QEMU, VirtualBox, and [vmd(8)](/vmd/8.md).

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.

## SEE ALSO

[intro(4)](/intro/4.md), [virtio(4)](/virtio/4.md)

## HISTORY

The **vio** driver first appeared in OpenBSD 5.3.

## AUTHORS

The **vio** driver was ported to OpenBSD and improved by Stefan Fritsch ⟨*sf@sfritsch.de*⟩. It is based on the NetBSD **vioif** driver by Minoura Makoto.