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

# rdmsr(1)

tool for reading CPU machine specific registers (MSR)

## NAME

rdmsr - tool for reading CPU machine specific registers (MSR)

## SYNOPSIS

**rdmsr \[options\] regno**

## DESCRIPTION

**rdmsr** is a tool used for reading 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 **rdmsr** not being able to open files in /dev/cpu/...

## OPTIONS

- **--help, -h**

  Print a list of available options

- **--version, -V**

  Print current version

- **--hexadecimal, -x**

  Display output in hexadecimal (lower case)

- **--capital-hex, -X**

  Display output in hexadecimal (upper case)

- **--decimal, -d**

  Display output in signed decimal

- **--unsigned, -u**

  Display output in unsigned decimal

- **--octal, -o**

  Display output in octal

- **--c-language, -c**

  Format output as a C language constant

- **--zero-pad, -0**

  Output leading zeroes

- **--zero-pad, -0**

  Output leading zeroes

- **--raw, -r**

  Output raw binary

- **--all, -a**

  All processors

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

  Select processor number (default: 0)

- **--bitfield h:l, -f**

  Output bits \[h:l\] only

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

  ## SEE ALSO

## AUTHOR

**rdmsr** 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).