.\" Copyright (c) 2010 Konstantin Belousov .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/share/man/man4/aesni.4,v 1.3 2010/09/09 21:37:05 brueffer Exp $ .\" .Dd February 25, 2012 .Dt RDRAND 4 .Os .Sh NAME .Nm rdrand .Nd "driver for the RNG module on Intel CPUs" .Sh SYNOPSIS To compile this driver into the kernel, place the following lines in your kernel configuration file: .Bd -ragged -offset indent .Cd "device rdrand" .Ed .Pp Alternatively, to load the driver as a module at boot time, place the following line in .Xr loader.conf 5 : .Bd -literal -offset indent rdrand_load="YES" .Ed .Sh DESCRIPTION WARNING: This driver is still untested. .Pp Starting with some models of the Ivy Bridge Core i5/i7, Intel processors implement a new set of instructions called RdRand. This set of instructions uses a hardware based RNG providing high-speed true randomness. .Pp The processor capability is reported as RDRND in the Features2 line at boot. The .Nm driver does not attach on systems that lack the required CPU capability. .Pp The .Nm driver continuously feeds entropy to the kernel's random number generator. .Sh SEE ALSO .Xr intro 4 , .Xr padlock 4 , .Xr random 4 .Sh HISTORY The .Nm driver first appeared in .Dx 3.1 . .Sh AUTHORS .An -nosplit The .Nm driver was written by .An Alex Hornung Aq alex@alexhornung.com .