EST(4) | Device Drivers Manual (x86) | 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.cpu.frequency.target`
  The target frequency of the CPUs.
`machdep.cpu.frequency.current`
  The current frequency.
`machdep.cpu.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), x86/odcm(4), x86/powernow(4)

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

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

# 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 x86/ichlpcib(4) or piixpcib(4) provide support for SpeedStep, the PCI-based interfaces should not be accessed due possible race conditions.

September 7, 2020 | NetBSD 10.1