MSR(4)                                              Linux Programmer's Manual                                             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 3.25 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/.



Linux                                                      2009-03-31                                                     MSR(4)