1.\" $NetBSD: viornd.4,v 1.3 2020/11/04 15:24:56 kim Exp $ 2.\" 3.\" Copyright (c) 2014 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Thor Lancelot Simon. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd October 26, 2014 31.Dt VIORND 4 32.Os 33.Sh NAME 34.Nm viornd 35.Nd VirtIO entropy source 36.Sh SYNOPSIS 37.Cd "viornd* at virtio?" 38.Sh DESCRIPTION 39When the system has entropy demand, 40the 41.Nm 42driver, used with a compatible hypervisor such as QEMU, KVM, or Google 43Compute Engine, requests entropy using the VirtIO random number interface 44and feeds it into the system entropy pool. 45.Sh SEE ALSO 46.Xr rnd 4 , 47.Xr virtio 4 48.Sh HISTORY 49The 50.Nm 51driver appeared in 52.Ox 5.5 . 53.Sh AUTHORS 54.An -nosplit 55The 56.Nm 57driver was written by 58.An Stephan Fritsch Aq Mt sf@fritsch.de 59and reworked to request entropy upon demand by 60.An Thor Lancelot Simon Aq Mt tls@NetBSD.org . 61.Sh CAVEATS 62VirtIO appears to support at least 8 pending entropy requests, but 63.Nm 64currently supports only one pending request at a time. 65