cpuid(4) [centos man page]

CPUID(4)						     Linux Programmer's Manual							  CPUID(4)

NAME

       cpuid - x86 CPUID access device

DESCRIPTION

       CPUID provides an interface for querying information about the x86 CPU.

       This device is accessed by lseek(2) or pread(2) to the appropriate CPUID level and reading in chunks of 16 bytes.  A larger read size means
       multiple reads of consecutive levels.

       The lower 32 bits of the file position is used as the incoming %eax, and the upper 32 bits of the file position as the incoming	%ecx,  the
       latter intended for "counting" eax levels like eax=4.

       This  driver uses /dev/cpu/CPUNUM/cpuid, where CPUNUM is the minor number, and on an SMP box will direct the access to CPU CPUNUM as listed
       in /proc/cpuinfo.

       This file is protected so that it can be read only by the user root, or members of the group root.

NOTES

       The CPUID instruction can be directly executed by a program using inline assembler.  However this device allows convenient  access  to  all
       CPUs without changing process affinity.

       Most  of  the  information  in  cpuid  is  reported  by	the  kernel  in  cooked  form either in /proc/cpuinfo or through subdirectories in
       /sys/devices/system/cpu.  Direct CPUID access through this device should only be used in exceptional cases.

       The cpuid driver is not auto-loaded.  On modular kernels you might need to use the following command to load it explicitly before use:

	    $ modprobe cpuid

       There is no support for CPUID functions that require additional input registers.

       Very old x86 CPUs don't support CPUID.

SEE ALSO

       Intel Corporation, Intel 64 and IA-32 Architectures Software Developer's Manual Volume 2A: Instruction Set Reference, A-M, 3-180 CPUID ref-
       erence.

       Intel Corporation, Intel Processor Identification and the CPUID Instruction, Application note 485.

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2009-03-31								  CPUID(4)

LONGRUN(1)						      General Commands Manual							LONGRUN(1)

NAME

       Transmeta(TM) Crusoe(TM) LongRun(TM) utility

SYNOPSIS

       longrun [-c device] [-m device] [-hlpv] [-f flag] [-s low high]

DESCRIPTION

       The longrun utility is used to control and query LongRun settings on Transmeta Crusoe processors.

       -c device
	      Set the CPUID device.  The default CPUID device is /dev/cpu/0/cpuid.

       -m device
	      Set the MSR device.  The default CPUID device is /dev/cpu/0/msr.

       -h     Print help.

       -l     List LongRun information about available performance levels for the CPU.

	      The following values are reported on all Transmeta CPUs that implement LongRun.

		 %	An  available  performance  level, expressed as a percentage of range of available core CPU frequencies.  0 corresponds to
			the lowest available frequency and 100 corresponds to the highest.

		 MHz	The core CPU frequency at that level.

		 Volts	The core CPU voltage at that level.

		 usage	The power usage relative to the maximum performance level.

       -p     Print current LongRun settings and status: whether LongRun is enabled, whether LongRun Thermal Extensions are  active,  the  current
	      LongRun performance window (expressed as a percentile range), the current LongRun performance level (expressed as a percentile), and
	      the current LongRun flags.

       -v     Be more verbose.

       -f flag
	      Set a LongRun mode flag.	Currently, the two supported flags are performance and economy.  This controls whether the processor is in
	      "performance mode" or "economy mode".

       -s low high
	      Set  the	current  LongRun  performance  window  as a percentile range.  The low number cannot be greater than the high number.  The
	      minimum and maximum performance values accepted by the CPU are 0 and 100, respectively.

ENVIRONMENT

       No environment variables are used.

FILES

       This program requires that the Linux CPUID and MSR devices be compiled into the kernel (or  loaded  as  kernel  modules),  that	the  CPUID
       character device be readable, and that the MSR character device be both readable and writable.

SEE ALSO

       acpid(8), apmd(8), hdparm(8)

AUTHOR

       Daniel Quinlan <quinlan@transmeta.com>

								 February 14, 2001							LONGRUN(1)