1.\" $NetBSD: piixpcib.4,v 1.4 2007/11/23 13:06:09 xtraeme Exp $ 2.\" 3.\" Copyright (c) 2007 Stephan Meisinger 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 November 23, 2007 18.Dt PIIXPCIB 4 19.Os 20.Sh NAME 21.Nm piixpcib 22.Nd Intel PIIX4 PCI-ISA bridge with SpeedStep 23.Sh SYNOPSIS 24.Cd "piixpcib* at pci? dev ? function ?" 25.Cd "isa* at piixpcib?" 26.Sh DESCRIPTION 27The 28.Nm 29driver provides support for the Intel PIIX and compatible PCI-ISA Bridges 30with Intel's first generation SpeedStep. 31.Pp 32Frequency scaling is supported on Pentium III with two voltage modes, 33used by SpeedStep as power states low and high. 34The driver will switch into low power state by reducing voltage 35and frequency of the CPU. 36The factor depends on the processor itself, but 37will always reduce power consumption about 1/2. 38.Pp 39The user can manually control the CPU frequency with the 40.Xr sysctl 8 41program using the following node: 42.Bl -tag -width usscanner -offset indent 43.It machdep.speedstep_state = [0/1] 44.El 45.Sh SEE ALSO 46.Xr isa 4 , 47.Xr pci 4 , 48.Xr apmd 8 , 49.Xr sysctl 8 50.Sh HISTORY 51The 52.Nm 53driver first appeared in 54.Fx 5.5 55and then in 56.Nx 4.0 . 57.Sh AUTHORS 58.An -nosplit 59The current 60.Nm 61driver was written by 62.An Bruno Ducrot . 63It was ported to 64.Nx 65by 66.An Jared D. McNeill Aq jmcneill@NetBSD.org . 67