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CPUCTL(8)                   System Manager's Manual                  CPUCTL(8)

     cpuctl - program to control CPUs

     cpuctl [-v] command [arguments]

     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 the
              CPUs 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

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

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

     ucode [cpu] [file]
              This applies the microcode patch to CPUs.  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 show 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.

     /dev/cpuctl  control device
                  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

           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

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

     The cpuctl command first appeared in NetBSD 5.0.

NetBSD 8.99.34                  April 15, 2019                  NetBSD 8.99.34