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 be read and written only  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 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2009-03-31				MSR(4)