openipmi | IPMI abstraction layer

openipmi is a C library typically used in Internet of Things (IoT), Raspberry Pi, Arduino applications. openipmi has no bugs, it has no vulnerabilities and it has low support. However openipmi has a Non-SPDX License. You can download it from GitHub.

IPMI is a specification detailing how to detect and manage sensors in a system. It also specifies some chassis-level thing like power control, reset, FRU (Field Replaceable Unit) information, and watchdogs. However, IPMI has become much more than that. Vendors have added extensions to IPMI for doing many thing, including controlling LEDs, relays, character displays, and managing hot-swapping components. In general, it has become the "standard" way to handle hardware maintenance in a system. IPMI specifies a set of interconnected intelligent Management Controllers (MCs). Each MC is a small CPU that manages a set of sensors and/or output devices. The "main" MC is called the Baseboard Management Controller (BMC); it provides the external interfaces into the system. Each MC may have a set of Sensor Data Records (SDRs). An SDR details information about a sensor. Some SDR records also have information about entities, such as their name, the FRU information, and what other entities they are contained in. Entities are the physical objects in the system (boards, CPUs, fans, power supplies, etc.) A sensor is attached to the entity it monitors; the SDR record tell what entity a sensor monitors. IPMI specifies several external interfaces to the BMC. One set is local interfaces directly to a CPU, a local CPU connections is called a system interface. The other is external interfaces through a LAN, serial port, or modem. The external interfaces allow a system to be managed even when it is turned off, since the BMC is always powered when the system is plugged in. IPMI has a strong bent toward complete "chassis" systems, basically a box with one main board with CPUs; a BMC, and perhaps a few satellite MCs in things like power supplies. It is being rapidly adopted in "shelf" systems, which has a set of slots where you can plug in complete single-board computers. In shelf systems, the BMC becomes a central shelf manager that manages all the boards in the shelf. Although IPMI was not designed for this, it does a pretty good job of extending into this architecture.