OpenIPMI

OpenIPMI is an effort to create a full-function IPMI system to allow full access to all IPMI information on a server and to abstract it to a level that will make it easy to use. See the SourceForge page for the source code.

A nice overview of IPMI can be found here, if you are interested.

OpenIPMI consists of two main parts: A device driver that goes into the Linux kernel, and a user-level library that provides a higher-level abstraction of IPMI and generic services that can be used on any operation system.

IPMI Documents

A new document is being created to support OpenIPMI, it helps document a lot of IPMI proper and reduces (and hopefully eliminates) the need to look at the IPMI specification. It is still very rough and incomplete, but is probably useful in its current form. This is also included in current releases of OpenIPMI. It will be udpated as time goes by.

Linux IPMI driver

Note: If you are using RHEL3, RHEL4, or SLES9, Matt Domsch graciously maintains a web page with a tool and set of patches for keeping those releases' IPMI driver up to date.

The Open IPMI Linux device driver is designed as a full-function IPMI device driver with the following features:

Allows multiple users.
Allows multiple interfaces.
Allows both kernel and userland things to use the interface.
Fully supports the watchdog timer.
It works like IPMI drivers are supposed to. It tracks outgoing messages and matches up their responses automatically. It automatically fetches events, received messages, etc.
It supports interrupts (I have tested them now).
It has backwards-compatability modules for supporting the Radisys IPMI driver and the Intel IMB driver.
It's modular. You don't have to have the standard userland interface. You don't have to have the watchdog. Etc.
It supports generating an event on a panic.

If you use the code as a module with high-res timers, you might need this patch because some symbols are not exported from the high-res timer code.

The releases are on the sourceforge page. Each release has a release relative to a plain kernel.org kernel (eg linux-ipmi-2.6.13-v36.1.base.diff). There are generally no diffs from previous version for the 2.6 kernel as the patches are pushed into the kernel pretty quickly. For 2.4 kernels, there are sometimes diffs from the previous version. Support has ceased for the 2.4 kernel except for serious bug fixes. The patches present are:

linux-ipmi-<kernelversion>-<driverversion>-base.diff - The main driver changes. You need this.
linux-ipmi-<kernelversion>-<driverversion>-emu.diff - The IMB and Radisys driver emulators. You only need this if you need the emulation code.
linux-ipmi-<kernelversion>-<driverversion>-smb.diff - The SMBus driver, for using IPMI over an I2C bus per the IPMI 2.0 standard. To use this, you need the I2C patches, too.
linux-i2c-<kernelversion>-<driverversion>.diff - The basic I2C changes required for the SMBus driver to work. Note that you also need driver changes for the specific I2C driver you are using.
linux-i2c-<kernelversion>-<driverversion>-i801.diff - Driver changes for the I801 driver.
linux-nmi-<kernelversion>-<driverversion>.diff - Changes to the i386 and x86_64 NMI infrastructure to allow NMI handlers to plug in like normal interrupts. This is only required if you need to use the IPMI NMI watchdog timeout (the pretimeout). Otherwise you don't need this.

This document describes the design. The user's guide is what comes in the kernel Documentation directory.

The OpenIPMI Library

Raw access to IPMI is rather difficult to use. Parsing SDRs, scanning for devices on the IPMB bus, scanning for events, and handling all the pieces is rather complicated. The OpenIPMI library provides a higher-level abstraction of this, the user of the OpenIPMI library deals directly with sensors and entities and does not have to worry about the lower-level details of IPMI.

Note that the OpenIPMI library is not Linux-specific. It was written with an os-layer so it could be ported to other operating systems. Of course, it works by default on Linux, but I would like to see it running on other operating systems. It includes an IPMI LAN interface, an interface for the OpenIPMI driver, but interfaces for other drivers and connections could be written.

The OpenIPMI library also includes the ipmicmd program, a small program that lets you inject and receive messages. You can register for incoming commands, set your source IPMB address, and other nifty things, too.