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EST(4)			    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	imple-
       ment Intel Enhanced SpeedStep Technology	via acpi(4) and	the  acpi_perf
       interface accessors.  If	the default settings are not optimal, the fol-
       lowing 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  Fre-
	       quency 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	14.3			April 21, 2020				EST(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=est&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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