1msr(4)                     Kernel Interfaces Manual                     msr(4)
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NAME

6       msr - x86 CPU MSR access device
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DESCRIPTION

9       /dev/cpu/CPUNUM/msr  provides an interface to read and write the model-
10       specific registers (MSRs) of an x86 CPU.  CPUNUM is the number  of  the
11       CPU to access as listed in /proc/cpuinfo.
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13       The  register access is done by opening the file and seeking to the MSR
14       number as offset in the file, and then reading or writing in chunks  of
15       8  bytes.  An I/O transfer of more than 8 bytes means multiple reads or
16       writes of the same register.
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18       This file is protected so that it can be read and written only  by  the
19       user root, or members of the group root.
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NOTES

22       The  msr  driver is not auto-loaded.  On modular kernels you might need
23       to use the following command to load it explicitly before use:
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25           $ modprobe msr
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SEE ALSO

28       Intel Corporation Intel 64 and IA-32 Architectures Software Developer's
29       Manual Volume 3B Appendix B, for an overview of the Intel CPU MSRs.
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33Linux man-pages 6.05              2022-10-30                            msr(4)