EST(4)                  NetBSD Kernel Interfaces Manual                 EST(4)

est -- Enhanced SpeedStep
est0 at cpu0
The est driver provides support for Enhanced SpeedStep introduced in Intel's first and second generation of Pentium M processors. The follow- ing sysctl(8) variables are available with est: 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.
acpicpu(4), x86/odcm(4), x86/powernow(4) Intel Corporation, Intel Pentium M Processor. Datasheet,, March, 2004. Intel Corporation, Enhanced Intel SpeedStep Technology for the Intel Pentium M Processor. White Paper,, March, 2004.
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) pro- vide support for SpeedStep, the PCI-based interfaces should not be accessed due possible race conditions. NetBSD 9.0 February 17, 2017 NetBSD 9.0

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