LIBMSR

Welcome to Libmsr, a friendly (well, friendlier) interface to many of the model-specific registers in Intel processors. Now with PCI configuration register support for some Intel hardware.

version 0.3.0

Last Update

24 August 2016

Webpages

http://software.llnl.gov/libmsr
https://github.com/llnl/libmsr

Overview

Libmsr provides an interface to accessing the model-specific registers (MSRs) on Intel platforms, which provide privileged functionality for monitoring and controlling various CPU features.

Installation

Installation is simple. You will need CMAKE version 2.8 or higher and GCC. The old installation method is deprecated, you MUST use the script. In most cases, the installation is as follows:

install.sh [ /path/to/install ] [ -f arch_model ]

The install script can take two (optional) arguments. The first argument is the install directory. If a null or empty string is specified, then a BUILD/ directory is automatically created in the top-level directory (i.e, where install.sh is launched from).

The second argument can explicitly tell the auto-configuration tool to use the header file of a specific architecture. To do this, simply add the following flag when executing the install script: "-f[architecture number]", where the architecture number is in hexadecimal.

Example:

I have an Ivy Bridge client processor which the auto-configuration tool does not detect. So, I will force the auto-configuration tool to use the Ivy Bridge header file defined in platform_headers/.

install.sh ~/build/libmsr -f3E

Currently supported architectures are Intel Xeon v1-3 (Sandy Bridge, Ivy Bridge, and Haswell server processors). The library technically supports all processors based on these architectures, but some features may be missing from client products. Using the wrong header file is likely to cause problems.

Supported Architectures:

2D (Sandy Bridge)
3E (Ivy Bridge)
3F (Haswell)

If you are unsure of your architecture number, check the "model" field in lscpu or /proc/cpuinfo (note that it won't be in hexadecimal).

Notes

This software depends on the files /dev/cpu/*/msr being present with R/W permissions. Recent kernels require additional capabilities. We have found it easier to use our own MSR-SAFE kernel module, but running as root (or going through the bother of adding the capabilities to the binaries) is another option.

If you need PCI configuration register (CSR) support in Libmsr, you MUST have CSR-SAFE installed. This code is not currently on Github – you will need to request it.

Call msr_init() before using any of the APIs.

For sample code, see libmsr_test.c in the test/ directory.

Our most up-to-date documentation for Libmsr use is generated as part of the install script using Doxygen. There are also some useful PDF files in the documentation/ directory.

If you wish to use Libmsr on LLNL's Cab system, you will need to apply a patch to gain MSR access. At this time, the patch will need to be requested as it is not on Github.

Contributing

Code formatting can be automated using astyle with the following parameters:

astyle --style=allman --indent=spaces=4 -y -S -C -N <src_file>

Contact

Barry Rountree, Project Lead, rount.nosp@m.ree@.nosp@m.llnl..nosp@m.gov
Kathleen Shoga, Developer, shoga.nosp@m.1@ll.nosp@m.nl.go.nosp@m.v
Scott Walker, Developer, walke.nosp@m.r91@.nosp@m.llnl..nosp@m.gov
Lauren Morita, Developer, morit.nosp@m.a4@l.nosp@m.lnl.g.nosp@m.ov
Stephanie Labasan, Developer, labas.nosp@m.an1@.nosp@m.llnl..nosp@m.gov

Please feel free to contact the developers with any questions or feature requests.