MirOS Manual: cpu(4)

CPU(4)                  BSD Programmer's Manual (i386)                  CPU(4)

NAME

     cpu - Central Processing Unit

SYNOPSIS

     option I386_CPU
     option I486_CPU
     option I586_CPU
     option I686_CPU

DESCRIPTION

     Several processor models have additional features that extend their base
     functionality, such as power and frequency control or additonal instruc-
     tions.

FREQUENCY CONTROL

     The sysctl(3) hw.cpuspeed will return the current operating frequency of
     the processor. If possible, speed may be adjusted by altering hw.setperf
     from 0 to 100, representing percentage of maximum speed. There are
     several possible implementations for setperf, all transparent to the
     user. In systems with more than one control capability, they are pre-
     ferred in the order given.

     LongRun     Found on Transmeta Crusoe processors, offers frequency scal-
                 ing with numerous positions. The processor dynamically ad-
                 justs frequency in response to load, the setperf value is in-
                 terpreted as the maximum.

     EST         Enhanced SpeedStep found on Intel Pentium M processors,
                 offers frequency scaling with numerous positions.

     SpeedStep   Found on some Intel Pentium 3 and newer mobile chips, it is
                 capable of adjusting frequency between a low and high value.
                 Only enabled on some chipsets.

     TCC         Thermal Control Circuit found on Intel Pentium 4 and newer
                 processors, adjusts processor duty cycle in 12.5 percent in-
                 crements.

     PowerNow    Found on various AMD processors. Currently only supports some
                 models in the K6 family.

INSTRUCTION SET EXTENSIONS

     The presence of extended instruction sets can be determined by sysctl
     machdep.

     osfxsr      Supports the fxsave instruction.

     sse         Supports the SSE instruction set.

     sse2        Supports the SSE2 instruction set.

     xcrypt      Support the VIA AES encryption instruction set. If this is
                 supported, the libcrypto EVP AES functions will automatically
                 use this support.

SEE ALSO

     ichpcib(4), npx(4), sysctl(8)

MirOS BSD #10-current           March 15, 2004                               1

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