Name
msr - x86 CPU MSR access deviceDescription
/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.