---
name: "est"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/est"
---

# est(4)

Enhanced Speedstep Technology

## 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)](/cpufreq/4.md) driver.

## LOADER TUNABLES

The **est** interface is intended to allow [cpufreq(4)](/cpufreq/4.md) to access and implement Intel Enhanced SpeedStep Technology via [acpi(4)](/acpi/4.md) 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)](/sysctl/8.md) 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)](/cpufreq/4.md) *Intel 64 and IA-32 Architectures Software Developer Manuals*, https://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*⟩.