CPUCTL(8)

NAME
cpuctl - program to control CPUs

SYNOPSIS
cpuctl [-v] command [arguments]

DESCRIPTION
The cpuctl command can be used to control and inspect the state of CPUs in the system.

The first argument, command, specifies the action to take. Valid commands are:

identify cpu [cpu ...]
    Output information on the specified CPU's features and capabilities. Not available on all architectures.

list
    For each CPU in the system, display the current state and time of the last state change.

offline cpu [cpu ...]
    Set the specified CPUs off line.

    Unbound LWPs (lightweight processes) will not be executed on a CPU while it is off line. Bound LWPs will continue to be executed on the CPUs, and device interrupts routed to the CPUs will continue to be handled. A future release of the system may allow device interrupts to be re-routed away from individual CPUs.

    At least one CPU in the system must remain on line.

online cpu [cpu ...]
    Set the specified CPUs on line, making them available to run unbound LWPs.

ucode
    [cpu] [file] This applies the microcode patch to CPUs. Unless -v was given, errors indicating that the microcode already exists on the CPU in question are ignored. If cpu is not specified or -1, all CPUs are updated. If cpu is -2, the current CPUs are updated. The default filename is used if no filename is specified. The identify command prints the installed version on the specified CPUs. On success the identify command shows different ucode versions before and after this command. The ucode updates are found in the default firmware path found in sysctl hw.firmware.path.

intr cpu [cpu ...]
    Enable interrupts for the specified CPUs if supported.

nointr cpu [cpu ...]
    Disable interrupts for the specified CPUs if supported.

Valid flags are:

-v  Be more verbose.

FILES
/dev/cpuctl
    control device
/libdata/firmware/x86/amd/
    The directory to install the microcode file for AMD CPUs into. The default filename is microcode_amd.bin for CPU families 0x10 to 0x14. The default filename is microcode_amd_famXXh.bin where XX is the CPU family starting with 15 (hex). Get it from https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/amd-ucode

EXAMPLES
Run
    cpuctl identify 0
and you should see something like this:

    cpu0: UCode version: 0x1000080

After applying the microcode patch with
    cpuctl ucode 0
you can see with
    cpuctl identify 0
that the patch got applied:

    cpu0: UCode version: 0x1000083

SEE ALSO
intrctl(8), psrset(8), schedctl(8), sysctl(8), firmload(9)

HISTORY
The cpuctl command first appeared in NetBSD 5.0.