PIIXPCIB(4)						   BSD 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
     consumption about 1/2.

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

	   machdep.speedstep_state = [0/1]

SEE ALSO

     est(4), 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>.

BSD
								   March 1, 2011							       BSD