---
name: "wrmsr"
section: "1"
platform: "linux"
package: "msr-tools"
version: "1.3+git20220805.7d78c80-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/wrmsr"
---

# wrmsr(1)

tool for writing CPU machine specific registers (MSR)

## NAME

wrmsr - tool for writing CPU machine specific registers (MSR)

## SYNOPSIS

**wrmsr \[options\] regno value**

## DESCRIPTION

**wrmsr** is a tool used for writing values to a CPU's machine specific registers (MSR).\
 Note: if you're running a Debian kernel, be sure that the msr.ko kernel module is loaded. 'modprobe msr' should do the trick. Otherwise, you'll get an error about **wrmsr** not being able to open files in /dev/cpu/...

## OPTIONS

- **--help, -h**

  Print a list of available options

- **--version, -V**

  Print current version

- **--all, -a**

  All processors

- **--processor \<#\>, -p**

  Select processor number (default: 0)

- **[rdmsr(1)](/rdmsr/1.md)**

  ## SEE ALSO

## AUTHOR

**wrmsr** was written by Transmeta Corporation

This man page was contributed by Andres Salomon \<dilinger@debian.org\> for the Debian GNU/Linux system (but may be used by others).