EST(4) | Kernel Interfaces Manual | EST(4)

# NAME

est — Enhanced SpeedStep

# SYNOPSIS

est0 at cpu0

# DESCRIPTION

The est driver provides support for Enhanced SpeedStep introduced in Intel's first and second generation of Pentium M processors. The following sysctl(8) variables are available with est:

machdep.est.frequency.target
  The target frequency of the CPUs.
machdep.est.frequency.current
  The current frequency.
machdep.est.frequency.available
  The frequencies recognized by est.

Note, however, that these variables are not guaranteed to exist in the future versions of NetBSD.

# SEE ALSO

acpicpu(4), odcm(4), powernow(4)

Intel Corporation, Intel Pentium M Processor., Datasheet, March, 2004, http://download.intel.com/support/processors/mobile/pm/sb/25261203.pdf.

Intel Corporation, Enhanced Intel SpeedStep Technology for the Intel Pentium M Processor., White Paper, March, 2004, http://download.intel.com/design/network/papers/30117401.pdf.

# CAVEATS

The est driver is considered a legacy interface to be used only with old systems. It is known to be problematic with new CPUs. Furthermore, in the unlikely case where both est and ichlpcib(4) or piixpcib(4) provide support for SpeedStep, the PCI-based interfaces should not be accessed due possible race conditions.

October 20, 2011 | NetBSD 6.0