est(4) - NetBSD Manual Pages

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EST(4)                NetBSD/x86 Kernel Interfaces Manual               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 follow-
     ing 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) pro-
     vide support for SpeedStep, the PCI-based interfaces should not be
     accessed due possible race conditions.

NetBSD 10.1                    September 7, 2020                   NetBSD 10.1