This article aims to help users implement services to actively monitor, log, and report hardware errors. A machine check exception (MCE) is an error generated by the CPU when the CPU detects that a hardware error or failure has occurred.

Machine check exceptions (MCEs) can occur for a variety of reasons ranging from undesired or out-of-spec voltages from the power supply, from cosmic radiation flipping bits in memory DIMMs or the CPU, or from other miscellaneous faults, including faulty software triggering hardware errors.

## Contents

*   [1 Installation](#Installation)
*   [2 Configuration](#Configuration)
*   [3 See also](#See_also)
    *   [3.1 Hardware documentation](#Hardware_documentation)

## Installation

[Install](/index.php/Install "Install") the [rasdaemon](https://aur.archlinux.org/packages/rasdaemon/) package. [rasdaemon](https://pagure.io/rasdaemon) written by Mauro Carvalho Chehab is one of the tools to gather MCE information.

Previously, the task was performed by the `mcelog` package. However, it has been deprecated, and Arch kernels are not even compiled with the necessary configuration option CONFIG_X86_MCELOG_LEGACY ([FS#55657](https://bugs.archlinux.org/task/55657)) now.

## Configuration

There are two systemd services that need to be [started](/index.php/Start "Start") and enabled. `ras-mc-ctl.service` registers DIMM labels (from `/etc/ras/dimm_labels.d/`) with EDAC drivers. On consumer-grade motherboards it usually logs a `No dimm labels for <motherboard model>` error and does nothing. `rasdaemon.service` runs as a daemon and logs RAS events to [systemd journal](/index.php/Systemd_journal "Systemd journal").

See [ras-mc-ctl(8)](https://www.mankier.com/8/ras-mc-ctl) and [rasdaemon(1)](https://www.mankier.com/1/rasdaemon) for more information.

## See also

*   [Wikipedia:Machine_Check_Exception](https://en.wikipedia.org/wiki/Machine_Check_Exception "wikipedia:Machine Check Exception")
*   [Wikipedia:Machine_check_architecture](https://en.wikipedia.org/wiki/Machine_check_architecture "wikipedia:Machine check architecture")
*   [Rasdaemon initial announcement](https://lwn.net/Articles/543097/)
*   [RAS presentation](https://events.linuxfoundation.org/sites/events/files/slides/RAS_presentation_LinuxCon_NA_0.pdf)
*   [mcelog Home](http://www.mcelog.org/)
*   [mcelog References](http://www.mcelog.org/references.html)

### Hardware documentation

*   [AMD64 Architecture Programmer's Manual, Volume 2: System Programming](http://support.amd.com/us/Processor_TechDocs/APM_v2_24593.pdf)
*   [BIOS and Kernel Developer's Guide for AMD Athlon™ 64 and AMD Opteron™ Processors](http://support.amd.com/us/Processor_TechDocs/26094.PDF)