CPUCONTROL(8)           FreeBSD System Manager's Manual          CPUCONTROL(8)

NAME
     cpucontrol - control utility for the cpuctl(4) device

SYNOPSIS
     cpucontrol [-v] -m msr device
     cpucontrol [-v] -m msr=value device
     cpucontrol [-v] -m msr&=mask device
     cpucontrol [-v] -m msr|=mask device
     cpucontrol [-v] -i level device
     cpucontrol [-v] -i level,level_type device
     cpucontrol [-vn] [-d datadir] -u device
     cpucontrol -e device

DESCRIPTION
     The cpucontrol utility can be used to read and write arbitrary machine-
     specific CPU registers via the cpuctl(4) special device.  It can also be
     used to apply CPU firmware updates.

     The following options are available:

     -d datadir
             Directory paths where to look for microcode images.  The option
             can be specified multiple times.  The paths are added in order of
             the options appearance on the command line, default directories
             are appended after the user-supplied paths.

     -n      Do not look for the microcode images in the standard directories.
             Currently standard directory to look for the microcode update
             files is /usr/local/share/cpucontrol.

     -m msr  Show value of the specified MSR.  MSR register number should be
             given as a hexadecimal number.  The high word is printed first,
             then the low word is printed second.

     -m msr=value
             Store the value in the specified MSR register.  The value
             argument can be prefixed with ~ operator.  In this case the
             inverted value of argument will be stored in the register.

     -m msr&=mask
             Store the result of bitwise AND operation between mask and the
             current MSR value in the MSR register.  The mask argument can be
             prefixed with ~ operator.  In this case the inverted value of
             mask will be used.

     -m msr|=mask
             Store the result of bitwise OR operation between mask and the
             current MSR value in the MSR register.  The mask argument can be
             prefixed with ~ operator.  In this case the inverted value of
             mask will be used.

     -i level
             Retrieve CPUID info.  Level should be given as a hex number.

     -i level,level_type
             Retrieve CPUID info.  Level and level_type should be given as hex
             numbers.

     -u      Apply CPU firmware updates.  The cpucontrol utility will walk
             through the configured data directories and apply all firmware
             updates available for this CPU.

     -e      Re-evaluate the kernel flags indicating the present CPU features.
             This command is typically executed after a firmware update was
             applied which changes information reported by the CPUID
             instruction.

             Only execute the -e command after the microcode update was
             applied to all CPUs in the system.  The kernel does not operate
             correctly if the features of processors are not identical.

     -v      Increase the verbosity level.

     -h      Show help message.

EXIT STATUS
     The cpucontrol utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     The command

     "cpucontrol -m 0x10 /dev/cpuctl0"

     will read the contents of TSC MSR from CPU 0.

     To set the CPU 0 TSC MSR register value to 0x1 issue

     "cpucontrol -m 0x10=0x1 /dev/cpuctl0".

     The following command will clear the second bit of TSC register:

     "cpucontrol -m 0x10&=~0x02 /dev/cpuctl0".

     The following command will set the forth and second bit of TSC register:

     "cpucontrol -m 0x10|=0x0a /dev/cpuctl0".

     The command

     "cpucontrol -i 0x1 /dev/cpuctl1"

     will retrieve the CPUID level 0x1 from CPU 1.

     To perform firmware updates on CPU 0 from images located at
     /usr/local/share/cpuctl use the following command:

     "cpucontrol -nd /usr/local/share/cpuctl -u /dev/cpuctl0"

SEE ALSO
     cpuctl(4)

HISTORY
     The cpucontrol utility first appeared in FreeBSD 7.2.

AUTHORS
     The cpucontrol utility and this manual page was written by Stanislav
     Sedov <stas@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6         January 5, 2018        FreeBSD 13.1-RELEASE-p6