PIIXPCIB(4)             NetBSD Kernel Interfaces Manual            PIIXPCIB(4)

NAME
     piixpcib -- Intel PIIX4 PCI-ISA bridge with SpeedStep

SYNOPSIS
     piixpcib* at pci? dev ? function ?
     isa* at piixpcib?

DESCRIPTION
     The piixpcib driver provides support for the Intel PIIX and compatible
     PCI-ISA Bridges with Intel's first generation SpeedStep.

     Frequency scaling is supported on Pentium III with two voltage modes,
     used by SpeedStep as power states low and high.  The driver will switch
     into low power state by reducing voltage and frequency of the CPU.  The
     factor depends on the processor itself, but will always reduce power con-
     sumption about 1/2.

     The user can manually control the CPU frequency with the sysctl(8) pro-
     gram using the following node:

           machdep.speedstep_state = [0/1]

SEE ALSO
     isa(4), pci(4), apmd(8), sysctl(8)

HISTORY
     The piixpcib driver first appeared in FreeBSD 5.5 and then in NetBSD 4.0.

AUTHORS
     The current piixpcib driver was written by Bruno Ducrot.  It was ported
     to NetBSD by Jared D. McNeill <jmcneill@NetBSD.org>.

NetBSD 5.0_STABLE              November 23, 2007             NetBSD 5.0_STABLE
