est(4) - NetBSD Manual Pages

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EST(4)                  NetBSD 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.est.frequency.target     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.


SEE ALSO

     acpicpu(4), odcm(4), 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 ichlpcib(4) or piixpcib(4) provide
     support for SpeedStep, the PCI-based interfaces should not be accessed
     due possible race conditions.

NetBSD 6.1.3                   October 20, 2011                   NetBSD 6.1.3