MSR(4)

NAME
msr - x86 CPU MSR access device

DESCRIPTION
/dev/cpu/CPUNUM/msr provides an interface to read and write the model-specific registers (MSRs) of an x86 CPU. CPUNUM is the number of the CPU to access as listed in /proc/cpuinfo.

The register access is done by opening the file and seeking to the MSR number as offset in the file, and then reading or writing in chunks of 8 bytes. An I/O transfer of more than 8 bytes means multiple reads or writes of the same register.

This file is protected so that it can only be read and written by the user root, or members of the group root.

NOTES
The msr driver is not auto-loaded. On modular kernels you might need to use the following command to load it explicitly before use:

    $ modprobe msr

SEE ALSO
Intel Corporation Intel 64 and IA-32 Architectures Software Developer's Manual Volume 3B Appendix B, for an overview of the Intel CPU MSRs.

COLOPHON
This page is part of release 3.50 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.