1.\" $NetBSD: est.4,v 1.7 2020/11/14 20:04:46 wiz Exp $ 2.\" 3.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Neither the name of the author nor the names of any 12.\" contributors may be used to endorse or promote products derived 13.\" from this software without specific prior written permission. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS 16.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 17.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 18.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 19.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25.\" POSSIBILITY OF SUCH DAMAGE. 26.\" 27.Dd September 7, 2020 28.Dt EST 4 x86 29.Os 30.Sh NAME 31.Nm est 32.Nd Enhanced SpeedStep 33.Sh SYNOPSIS 34.Cd "est0 at cpu0" 35.Sh DESCRIPTION 36The 37.Nm 38driver provides support for Enhanced SpeedStep introduced in 39Intel's first and second generation of Pentium M processors. 40The following 41.Xr sysctl 8 42variables are available with 43.Nm : 44.Bl -tag -width "machdep.cpu.frequency.available" -offset indent 45.It Ic machdep.cpu.frequency.target 46The target frequency of the 47.Tn CPUs . 48.It Ic machdep.cpu.frequency.current 49The current frequency. 50.It Ic machdep.cpu.frequency.available 51The frequencies recognized by 52.Nm . 53.El 54.Pp 55Note, however, that these variables are 56not guaranteed to exist in the future versions of 57.Nx . 58.Sh SEE ALSO 59.Xr acpicpu 4 , 60.Xr x86/odcm 4 , 61.Xr x86/powernow 4 62.Rs 63.%A Intel Corporation 64.%T Intel Pentium M Processor. 65.%T Datasheet 66.%D March, 2004 67.%U http://download.intel.com/support/processors/mobile/pm/sb/25261203.pdf 68.Re 69.Rs 70.%A Intel Corporation 71.%T Enhanced Intel SpeedStep Technology for the Intel Pentium M Processor. 72.%T White Paper 73.%D March, 2004 74.%U http://download.intel.com/design/network/papers/30117401.pdf 75.Re 76.Sh CAVEATS 77The 78.Nm 79driver is considered a legacy interface to be used only with old systems. 80It is known to be problematic with new 81.Tn CPUs . 82Furthermore, in the unlikely case where both 83.Nm 84and 85.Xr x86/ichlpcib 4 86or 87.Xr piixpcib 4 88provide support for SpeedStep, 89the PCI-based interfaces should not be accessed due possible race conditions. 90