1.\" $OpenBSD: vio.4,v 1.16 2021/05/24 17:29:56 dv Exp $ 2.\" 3.\" Copyright (c) 2012 Stefan Fritsch <sf@sfritsch.de> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: May 24 2021 $ 18.Dt VIO 4 19.Os 20.Sh NAME 21.Nm vio 22.Nd VirtIO network device 23.Sh SYNOPSIS 24.Cd "vio* at virtio? flags 0x00" 25.Sh DESCRIPTION 26The 27.Nm 28driver provides support for the 29.Xr virtio 4 30network interface provided by bhyve, KVM, QEMU, VirtualBox, and 31.Xr vmd 8 . 32.Pp 33Setting the bit 0x2 in the flags disables the RingEventIndex feature. 34This can be tried as a workaround for possible bugs in host implementations of 35.Nm 36at the cost of slightly reduced performance. 37.Pp 38Setting the bit 0x100 in the flags forces the interface to be always in 39promiscuous mode. 40This can be used as a workaround for a bug in QEMU before version 1.7.2 that 41prevents packets with a VLAN tag from being sent to the guest. 42.Sh SEE ALSO 43.Xr intro 4 , 44.Xr virtio 4 45.Sh HISTORY 46The 47.Nm 48driver first appeared in 49.Ox 5.3 . 50.Sh AUTHORS 51.An -nosplit 52The 53.Nm 54driver was ported to 55.Ox 56and improved by 57.An Stefan Fritsch Aq Mt sf@sfritsch.de . 58It is based on the 59.Nx 60.Nm vioif 61driver by 62.An Minoura Makoto . 63