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+.\" Copyright (c) 2009 Intel Corporation, Author Andi Kleen
+.\" Some sentences copied from comments in arch/x86/kernel/msr.c
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH msr 4 2022-10-30 "Linux man-pages 6.05.01"
+.SH NAME
+msr \- x86 CPU MSR access device
+.SH DESCRIPTION
+.I /dev/cpu/CPUNUM/msr
+provides an interface to read and write the model-specific
+registers (MSRs) of an x86 CPU.
+.I CPUNUM
+is the number of the CPU to access as listed in
+.IR /proc/cpuinfo .
+.PP
+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.
+.PP
+This file is protected so that it can be read and written only by the user
+.IR root ,
+or members of the group
+.IR root .
+.SH NOTES
+The
+.I msr
+driver is not auto-loaded.
+On modular kernels you might need to use the following command
+to load it explicitly before use:
+.PP
+.in +4n
+.EX
+$ modprobe msr
+.EE
+.in
+.SH 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.