EST(4)                 FreeBSD Kernel Interfaces Manual                 EST(4)

NAME
     est - Enhanced Speedstep Technology

SYNOPSIS
     To compile this capability into your kernel place the following line in
     your kernel configuration file:

           device cpufreq

DESCRIPTION
     The est interface provides support for the Intel Enhanced Speedstep
     Technology.

     Note that est capabilities are automatically loaded by the cpufreq(4)
     driver.

LOADER TUNABLES
     The est interface is intended to allow cpufreq(4) to access and implement
     Intel Enhanced SpeedStep Technology via acpi(4) and the acpi_perf
     interface accessors.  If the default settings are not optimal, the
     following sysctls can be used to modify or monitor est behavior.

     hw.est.msr_info
             Attempt to infer information from direct probing of the msr.
             Should only be used in diagnostic cases.  (default 0)

     hw.est.strict
             Validate frequency requested is accepted by the CPU when set.  It
             appears that this will only work on single core cpus.  (default
             0)

SYSCTL VARIABLES
     The following sysctl(8) values are available

     dev.est.%d.%desc
             Description of support, almost always Enhanced SpeedStep
             Frequency Control.

     dev.est.0.%desc: Enhanced SpeedStep Frequency Control

     dev.est.%d.%driver
             Driver in use, always est.

     dev.est.0.%driver: est

     dev.est.%d.%parent
             The CPU that is exposing these frequencies.  For example cpu0.

     dev.est.0.%parent: cpu0

     dev.est.%d.freq_settings.
             The valid frequencies that are allowed by this CPU and their step
             values.

     dev.est.0.freq_settings: 2201/45000 2200/45000 2000/39581 1900/37387
             1800/34806 1700/32703 1600/30227 1500/28212 1400/25828 1300/23900
             1200/21613 1100/19775 1000/17582 900/15437 800/13723

DIAGNOSTICS
     est%d: <Enhanced SpeedStep Frequency Control> on cpu%d

     Indicates normal startup of this interface.

     est: CPU supports Enhanced Speedstep, but is not recognized.
     est: cpu_vendor GenuineIntel, msr 471c471c0600471c
     device_attach: est%d attach returned 6

     Indicates all attempts to attach to this interface have failed.  This
     usually indicates an improper BIOS setting restricting O/S control of the
     CPU speeds.  Consult your BIOS documentation for more details.

COMPATIBILITY
     est is only found on supported Intel CPUs.

SEE ALSO
     cpufreq(4)

     Intel 64 and IA-32 Architectures Software Developer Manuals,
     http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html.

AUTHORS
     This manual page was written by Sean Bruno <sbruno@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6         April 21, 2020         FreeBSD 13.1-RELEASE-p6