NAME
piixpcib —
Intel PIIX4 PCI-ISA bridge with
SpeedStep
SYNOPSIS
piixpcib* at pci? dev ? function ?
isa* at piixpcib?
DESCRIPTION
Thepiixpcib 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
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>.