HardenedBSD/usr.sbin/cpucontrol/cpucontrol.8

.\" Copyright (c) 2006, 2008 Stanislav Sedov <stas@FreeBSD.org>.
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.Dd January 5, 2018
.Dt CPUCONTROL 8
.Os
.Sh NAME
.Nm cpucontrol
.Nd control utility for the
.Xr cpuctl 4
device
.Sh SYNOPSIS
.Bk
.Nm
.Op Fl v
.Fl m Ar msr
.Ar device
.Ek
.Bk
.Nm
.Op Fl v
.Fl m Ar msr Ns = Ns Ar value
.Ar device
.Ek
.Bk
.Nm
.Op Fl v
.Fl m Ar msr Ns &= Ns Ar mask
.Ar device
.Ek
.Bk
.Nm
.Op Fl v
.Fl m Ar msr Ns |= Ns Ar mask
.Ar device
.Ek
.Bk
.Nm
.Op Fl v
.Fl i Ar level
.Ar device
.Ek
.Bk
.Nm
.Op Fl v
.Fl i Ar level,level_type
.Ar device
.Ek
.Bk
.Nm
.Op Fl vn
.Op Fl d Ar datadir
.Fl u
.Ar device
.Ek
.Bk
.Nm
.Fl e
.Ar device
.Ek
.Sh DESCRIPTION
The
.Nm
utility can be used to read and write arbitrary machine-specific
CPU registers via the
.Xr cpuctl 4
special device.
It can also be used to apply CPU firmware updates.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl d Ar 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.
.It Fl n
Do not look for the microcode images in the standard directories.
Currently standard directory to look for the microcode update files is
.Pa /usr/local/share/cpucontrol .
.It Fl m Ar 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.
.It Fl m Ar msr Ns = Ns Ar value
Store the
.Ar value
in the specified MSR register.
The
.Ar value
argument can be prefixed with ~ operator.
In this case the inverted value of argument will be stored in the register.
.It Fl m Ar msr Ns &= Ns Ar mask
Store the result of bitwise AND operation between
.Ar mask
and the current MSR value in the MSR register.
The
.Ar mask
argument can be prefixed with ~ operator.
In this case the inverted value of mask will be used.
.It Fl m Ar msr Ns |= Ns Ar mask
Store the result of bitwise OR operation between
.Ar mask
and the current MSR value in the MSR register.
The
.Ar mask
argument can be prefixed with ~ operator.
In this case the inverted value of mask will be used.
.It Fl i Ar level
Retrieve CPUID info.
Level should be given as a hex number.
.It Fl i Ar level,level_type
Retrieve CPUID info.
Level and level_type should be given as hex numbers.
.It Fl u
Apply CPU firmware updates.
The
.Nm
utility will walk through the configured data directories
and apply all firmware updates available for this CPU.
.It Fl 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
.Dv CPUID
instruction.
.Pp
.Bf -symbolic
Only execute the
.Fl 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.
.Ef
.It Fl v
Increase the verbosity level.
.It Fl h
Show help message.
.El
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
The command
.Pp
.Dq Li "cpucontrol -m 0x10 /dev/cpuctl0"
.Pp
will read the contents of TSC MSR from CPU 0.
.Pp
To set the CPU 0 TSC MSR register value to 0x1 issue
.Pp
.Dq Li "cpucontrol -m 0x10=0x1 /dev/cpuctl0" .
.Pp
The following command will clear the second bit of TSC register:
.Pp
.Dq Li "cpucontrol -m 0x10&=~0x02 /dev/cpuctl0" .
.Pp
The following command will set the forth and second bit of TSC register:
.Pp
.Dq Li "cpucontrol -m 0x10|=0x0a /dev/cpuctl0" .
.Pp
The command
.Pp
.Dq Li "cpucontrol -i 0x1 /dev/cpuctl1"
.Pp
will retrieve the CPUID level 0x1 from CPU 1.
.Pp
To perform firmware updates on CPU 0 from images located at
.Pa /usr/local/share/cpuctl
use the following command:
.Pp
.Dq Li "cpucontrol -nd /usr/local/share/cpuctl -u /dev/cpuctl0"
.Sh SEE ALSO
.Xr cpuctl 4
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 7.2 .
.Sh AUTHORS
The
.Nm
utility and this manual page was written by
.An Stanislav Sedov Aq Mt stas@FreeBSD.org .