68 lines
1.9 KiB
Groff
68 lines
1.9 KiB
Groff
.\" $NetBSD: piixpcib.4,v 1.6 2013/07/20 21:39:58 wiz Exp $
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.\"
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.\" Copyright (c) 2007 Stephan Meisinger
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd March 1, 2011
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.Dt PIIXPCIB 4
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.Os
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.Sh NAME
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.Nm piixpcib
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.Nd Intel PIIX4 PCI-ISA bridge with SpeedStep
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.Sh SYNOPSIS
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.Cd "piixpcib* at pci? dev ? function ?"
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.Cd "isa* at piixpcib?"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for the Intel PIIX and compatible PCI-ISA Bridges
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with Intel's first generation SpeedStep.
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.Pp
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Frequency scaling is supported on Pentium III with two voltage modes,
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used by SpeedStep as power states low and high.
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The driver will switch into low power state by reducing voltage
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and frequency of the CPU.
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The factor depends on the processor itself, but
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will always reduce power consumption about 1/2.
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.Pp
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The user can manually control the CPU frequency with the
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.Xr sysctl 8
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program using the following node:
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.Bl -tag -width usscanner -offset indent
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.It machdep.speedstep_state = [0/1]
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.El
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.Sh SEE ALSO
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.Xr est 4 ,
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.Xr isa 4 ,
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.Xr pci 4 ,
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.Xr apmd 8 ,
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.Xr sysctl 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 5.5
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and then in
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.Nx 4.0 .
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.Sh AUTHORS
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.An -nosplit
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The current
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.Nm
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driver was written by
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.An Bruno Ducrot .
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It was ported to
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.Nx
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by
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.An Jared D. McNeill Aq Mt jmcneill@NetBSD.org .
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