MSR(4) Linux Programmer's Manual MSR(4)NAME
msr - x86 CPU MSR access device
/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.
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
Intel Corporation Intel 64 and IA-32 Architectures Software Developer's Manual Volume 3B Appendix B, for an overview of the Intel CPU MSRs.
This page is part of release 4.15 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)
Check Out this Related Man Page
CPUID(4) Linux Programmer's Manual CPUID(4)NAME
cpuid - x86 CPUID access device
CPUID provides an interface for querying information about the x86 CPU.
This device is accessed by lseek (2) or pread (2) to the appropriate CPUID level and reading in chunks of 16 bytes. A larger read size
means multiple reads of consecutive levels.
The lower 32 bits of the file position is used as the incoming %eax, and the upper 32 bits of the file position as the incoming %ecx, the
latter intended for "counting" eax levels like eax=4.
This driver uses /dev/cpu/CPUNUM/cpuid, where CPUNUM is the minor number, and on an SMP box will direct the access to CPU CPUNUM as listed
This file is protected so that it can only be read by the user root, or members of the group root.
The CPUID instruction can be directly executed by a program using inline assembler. However this device allows convenient access to all
CPUs without changing process affinity.
Most of the information in cpuid is reported by the kernel in cooked form either in /proc/cpuinfo or through subdirectories in
/sys/devices/system/cpu. Direct CPUID access through this device should only be used in exceptional cases.
The cpuid driver is not auto-loaded. On modular kernels you might need to use the following command to load it explicitly before use:
$ modprobe cpuid
There is no support for CPUID functions that require additional input registers.
Very old x86 CPUs don't support CPUID.
Intel Corporation, Intel 64 and IA-32 Architectures Software Developer's Manual Volume 2A: Instruction Set Reference, A-M, 3-180 CPUID ref-
Intel Corporation, Intel Processor Identification and the CPUID Instruction, Application note 485.
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2009-03-31 CPUID(4)
I am working on MSR110 ...Can anyone plz tell me how to use the configuration commands with magnetic reader???. Please help me out as i have to develop API in C on linux platform.MSR110 is not responding to the configuration commands.
Mahima (0 Replies)