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.Dd May 17, 2019
.Dt CPUCTL 8
.Os
.Sh NAME
.Nm cpuctl
.Nd program to control CPUs
.Sh SYNOPSIS
.Nm cpuctl
.Op Fl v
.Ar command
.Op Ar arguments
.Sh DESCRIPTION
The
.Nm
command can be used to control and inspect the state of CPUs in the system.
.Pp
The first argument,
.Ar command ,
specifies the action to take.
Valid commands are:
.Bl -tag -width identify
.It identify Ar cpu Op Ar cpu ...
Output information on the specified CPU's features and capabilities.
Not available on all architectures.
.It list
For each CPU in the system, display the current state and time of the last
state change.
.It offline Ar cpu Op Ar cpu ...
Set the specified CPUs off line.
.Pp
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.
.Pp
At least one CPU in the system must remain on line.
.It online Ar cpu Op Ar cpu ...
Set the specified CPUs on line, making them available to run unbound LWPs.
.It ucode Xo
.Op Ar cpu
.Op Ar file
.Xc
This applies the microcode patch to CPUs.
Unless
.Fl v
was given, errors indicating that the microcode
already exists on the CPU in question are ignored.
If
.Ar cpu
is not specified or \-1, all CPUs are updated.
If
.Ar cpu
is \-2, the current CPUs are updated.
The default filename is used if no filename is specified.
The
.Cm identify
command prints the installed version on the specified CPUs.
On success the
.Cm 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.
.It intr Ar cpu Op Ar cpu ...
Enable interrupts for the specified CPUs if supported.
.It nointr Ar cpu Op Ar cpu ...
Disable interrupts for the specified CPUs if supported.
.El
.Pp
Valid flags are:
.Bl -tag -width indent
.It Fl v
Be more verbose.
.El
.Sh FILES
.Bl -tag -width /dev/cpuctl -compact
.It Pa /dev/cpuctl
control device
.It Pa /libdata/firmware/x86/amd/
The directory to install the microcode file for AMD CPUs into.
The default filename is
.Pa microcode_amd.bin
for CPU families 0x10 to 0x14.
The default filename is
.Pa microcode_amd_famXXh.bin
where
.Dv XX
is the CPU family starting with 15 (hex).
Get it from
.Lk https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/amd-ucode
.El
.Sh EXAMPLES
Run
.Dl cpuctl identify 0
and you should see something like this:
.Bd -literal -offset indent
cpu0: UCode version: 0x1000080
.Ed
.Pp
After applying the microcode patch with
.Dl cpuctl ucode 0
you can see with
.Dl cpuctl identify 0
that the patch got applied:
.Bd -literal -offset indent
cpu0: UCode version: 0x1000083
.Ed
.Sh SEE ALSO
.Xr intrctl 8 ,
.Xr psrset 8 ,
.Xr schedctl 8 ,
.Xr sysctl 8 ,
.Xr firmload 9
.Sh HISTORY
The
.Nm
command first appeared in
.Nx 5.0 .