]>
Commit | Line | Data |
---|---|---|
daad8dcd | 1 | .\" Copyright (c) 2009 Intel Corporation, Author Andi Kleen |
027ac74c AK |
2 | .\" Some sentences copied from comments in arch/x86/kernel/msr.c |
3 | .\" | |
5fbde956 | 4 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
027ac74c | 5 | .\" |
4c1c5274 | 6 | .TH msr 4 (date) "Linux man-pages (unreleased)" |
027ac74c AK |
7 | .SH NAME |
8 | msr \- x86 CPU MSR access device | |
9 | .SH DESCRIPTION | |
10 | .I /dev/cpu/CPUNUM/msr | |
11 | provides an interface to read and write the model-specific | |
12 | registers (MSRs) of an x86 CPU. | |
7c63ca6c MK |
13 | .I CPUNUM |
14 | is the number of the CPU to access as listed in | |
027ac74c | 15 | .IR /proc/cpuinfo . |
2dad4c59 | 16 | .PP |
027ac74c AK |
17 | The register access is done by opening the file and seeking |
18 | to the MSR number as offset in the file, and then | |
19 | reading or writing in chunks of 8 bytes. | |
20 | An I/O transfer of more than 8 bytes means multiple reads or writes | |
21 | of the same register. | |
2dad4c59 | 22 | .PP |
33a0ccb2 | 23 | This file is protected so that it can be read and written only by the user |
027ac74c AK |
24 | .IR root , |
25 | or members of the group | |
26 | .IR root . | |
27 | .SH NOTES | |
7c63ca6c | 28 | The |
027ac74c AK |
29 | .I msr |
30 | driver is not auto-loaded. | |
31 | On modular kernels you might need to use the following command | |
32 | to load it explicitly before use: | |
019d9ee8 MK |
33 | .PP |
34 | .in +4n | |
35 | .EX | |
54f011e7 | 36 | $ modprobe msr |
019d9ee8 MK |
37 | .EE |
38 | .in | |
027ac74c AK |
39 | .SH SEE ALSO |
40 | Intel Corporation Intel 64 and IA-32 Architectures | |
173fe7e7 | 41 | Software Developer's Manual Volume 3B Appendix B, |
027ac74c | 42 | for an overview of the Intel CPU MSRs. |