| CPUCTL(8) | System Manager's Manual | CPUCTL(8) | 
cpuctl —
| cpuctl | [ -v] command
      [arguments] | 
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:
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.
-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.Valid flags are:
-vXX 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-ucodecpuctl identify 0cpu0: UCode version: 0x1000080
After applying the microcode patch with
cpuctl ucode 0cpuctl identify 0cpu0: UCode version: 0x1000083
cpuctl command first appeared in
  NetBSD 5.0.
| May 17, 2019 | NetBSD 10.0 |