1.\" Copyright (c) 2010 Konstantin Belousov <kib@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD: src/share/man/man4/aesni.4,v 1.3 2010/09/09 21:37:05 brueffer Exp $ 26.\" 27.Dd February 25, 2012 28.Dt RDRAND 4 29.Os 30.Sh NAME 31.Nm rdrand 32.Nd "driver for the RNG module on Intel CPUs" 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following lines in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device rdrand" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45rdrand_load="YES" 46.Ed 47.Sh DESCRIPTION 48WARNING: This driver is still untested. 49.Pp 50Starting with some models of the Ivy Bridge Core i5/i7, Intel processors 51implement a new set of instructions called RdRand. 52This set of instructions uses a hardware based RNG providing 53high-speed true randomness. 54.Pp 55The processor capability is reported as RDRND in the Features2 line at boot. 56The 57.Nm 58driver does not attach on systems that lack the required CPU capability. 59.Pp 60The 61.Nm 62driver continuously feeds entropy to the kernel's random number generator. 63.Sh SEE ALSO 64.Xr intro 4 , 65.Xr padlock 4 , 66.Xr random 4 67.Sh HISTORY 68The 69.Nm 70driver first appeared in 71.Dx 3.1 . 72.Sh AUTHORS 73.An -nosplit 74The 75.Nm 76driver was written by 77.An Alex Hornung Aq Mt alex@alexhornung.com . 78