<!DOCTYPE html>
<html lang="en" data-content_root="../">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="viewport" content="width=device-width, initial-scale=1" />
<title>HPE iLO NMI Watchdog Driver — The Linux Kernel documentation</title>
<link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=fa44fd50" />
<link rel="stylesheet" type="text/css" href="../_static/alabaster.css?v=3918102e" />
<script src="../_static/documentation_options.js?v=5929fcd5"></script>
<script src="../_static/doctools.js?v=9bcbadda"></script>
<script src="../_static/sphinx_highlight.js?v=dc90522c"></script>
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="next" title="Mellanox watchdog drivers" href="mlx-wdt.html" />
<link rel="prev" title="Watchdog Support" href="index.html" />
<link rel="stylesheet" href="../_static/custom.css" type="text/css" />
</head><body>
<div class="document">
<div class="sphinxsidebar" role="navigation" aria-label="Main">
<div class="sphinxsidebarwrapper">
<p class="logo"><a href="../index.html">
<img class="logo" src="../_static/logo.svg" alt="Logo of The Linux Kernel"/>
</a></p>
<h1 class="logo"><a href="../index.html">The Linux Kernel</a></h1>
<p class="blurb">6.18.50</p>
<search id="searchbox" style="display: none" role="search">
<h3 id="searchlabel">Quick search</h3>
<div class="searchformwrapper">
<form class="search" action="../search.html" method="get">
<input type="text" name="q" aria-labelledby="searchlabel" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"/>
<input type="submit" value="Go" />
</form>
</div>
</search>
<script>document.getElementById('searchbox').style.display = "block"</script>
<p>
<h3 class="kernel-toc-contents">Contents</h3>
<input type="checkbox" class="kernel-toc-toggle" id = "kernel-toc-toggle" checked>
<label class="kernel-toc-title" for="kernel-toc-toggle"></label>
<div class="kerneltoc" id="kerneltoc">
<ul>
<li class="toctree-l1"><a class="reference internal" href="../process/development-process.html">Development process</a></li>
<li class="toctree-l1"><a class="reference internal" href="../process/submitting-patches.html">Submitting patches</a></li>
<li class="toctree-l1"><a class="reference internal" href="../process/code-of-conduct.html">Code of conduct</a></li>
<li class="toctree-l1"><a class="reference internal" href="../maintainer/index.html">Maintainer handbook</a></li>
<li class="toctree-l1"><a class="reference internal" href="../process/index.html">All development-process docs</a></li>
</ul>
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../core-api/index.html">Core API</a></li>
<li class="toctree-l1"><a class="reference internal" href="../driver-api/index.html">Driver APIs</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="../subsystem-apis.html">Subsystems</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="../subsystem-apis.html#core-subsystems">Core subsystems</a></li>
<li class="toctree-l2"><a class="reference internal" href="../subsystem-apis.html#human-interfaces">Human interfaces</a></li>
<li class="toctree-l2"><a class="reference internal" href="../subsystem-apis.html#networking-interfaces">Networking interfaces</a></li>
<li class="toctree-l2"><a class="reference internal" href="../subsystem-apis.html#storage-interfaces">Storage interfaces</a></li>
<li class="toctree-l2 current"><a class="reference internal" href="../subsystem-apis.html#other-subsystems">Other subsystems</a><ul class="current">
<li class="toctree-l3"><a class="reference internal" href="../accounting/index.html">Accounting</a></li>
<li class="toctree-l3"><a class="reference internal" href="../cpu-freq/index.html">CPUFreq - CPU frequency and voltage scaling code in the Linux(TM) kernel</a></li>
<li class="toctree-l3"><a class="reference internal" href="../edac/index.html">EDAC Subsystem</a></li>
<li class="toctree-l3"><a class="reference internal" href="../fpga/index.html">FPGA</a></li>
<li class="toctree-l3"><a class="reference internal" href="../i2c/index.html">I2C/SMBus Subsystem</a></li>
<li class="toctree-l3"><a class="reference internal" href="../iio/index.html">Industrial I/O</a></li>
<li class="toctree-l3"><a class="reference internal" href="../pcmcia/index.html">PCMCIA</a></li>
<li class="toctree-l3"><a class="reference internal" href="../spi/index.html">Serial Peripheral Interface (SPI)</a></li>
<li class="toctree-l3"><a class="reference internal" href="../w1/index.html">1-Wire Subsystem</a></li>
<li class="toctree-l3 current"><a class="reference internal" href="index.html">Watchdog Support</a></li>
<li class="toctree-l3"><a class="reference internal" href="../virt/index.html">Virtualization Support</a></li>
<li class="toctree-l3"><a class="reference internal" href="../hwmon/index.html">Hardware Monitoring</a></li>
<li class="toctree-l3"><a class="reference internal" href="../accel/index.html">Compute Accelerators</a></li>
<li class="toctree-l3"><a class="reference internal" href="../security/index.html">Security Documentation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../crypto/index.html">Crypto API</a></li>
<li class="toctree-l3"><a class="reference internal" href="../bpf/index.html">BPF Documentation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../usb/index.html">USB support</a></li>
<li class="toctree-l3"><a class="reference internal" href="../PCI/index.html">PCI Bus Subsystem</a></li>
<li class="toctree-l3"><a class="reference internal" href="../misc-devices/index.html">Assorted Miscellaneous Devices Documentation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../peci/index.html">PECI Subsystem</a></li>
<li class="toctree-l3"><a class="reference internal" href="../wmi/index.html">WMI Subsystem</a></li>
<li class="toctree-l3"><a class="reference internal" href="../tee/index.html">TEE Subsystem</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../locking/index.html">Locking</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../process/license-rules.html">Licensing rules</a></li>
<li class="toctree-l1"><a class="reference internal" href="../doc-guide/index.html">Writing documentation</a></li>
<li class="toctree-l1"><a class="reference internal" href="../dev-tools/index.html">Development tools</a></li>
<li class="toctree-l1"><a class="reference internal" href="../dev-tools/testing-overview.html">Testing guide</a></li>
<li class="toctree-l1"><a class="reference internal" href="../kernel-hacking/index.html">Hacking guide</a></li>
<li class="toctree-l1"><a class="reference internal" href="../trace/index.html">Tracing</a></li>
<li class="toctree-l1"><a class="reference internal" href="../fault-injection/index.html">Fault injection</a></li>
<li class="toctree-l1"><a class="reference internal" href="../livepatch/index.html">Livepatching</a></li>
<li class="toctree-l1"><a class="reference internal" href="../rust/index.html">Rust</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../admin-guide/index.html">Administration</a></li>
<li class="toctree-l1"><a class="reference internal" href="../kbuild/index.html">Build system</a></li>
<li class="toctree-l1"><a class="reference internal" href="../admin-guide/reporting-issues.html">Reporting issues</a></li>
<li class="toctree-l1"><a class="reference internal" href="../tools/index.html">Userspace tools</a></li>
<li class="toctree-l1"><a class="reference internal" href="../userspace-api/index.html">Userspace API</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../firmware-guide/index.html">Firmware</a></li>
<li class="toctree-l1"><a class="reference internal" href="../devicetree/index.html">Firmware and Devicetree</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../arch/index.html">CPU architectures</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../staging/index.html">Unsorted documentation</a></li>
</ul>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../translations/index.html">Translations</a></li>
</ul>
</div>
<script type="text/javascript"> <!--
var sbar = document.getElementsByClassName("sphinxsidebar")[0];
let currents = document.getElementsByClassName("current")
if (currents.length) {
sbar.scrollTop = currents[currents.length - 1].offsetTop;
}
--> </script>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../_sources/watchdog/hpwdt.rst.txt"
rel="nofollow">Show Source</a></li>
</ul>
</div>
</div>
</div>
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<section id="hpe-ilo-nmi-watchdog-driver">
<h1>HPE iLO NMI Watchdog Driver<a class="headerlink" href="#hpe-ilo-nmi-watchdog-driver" title="Link to this heading">¶</a></h1>
<section id="for-ilo-based-proliant-servers">
<h2>for iLO based ProLiant Servers<a class="headerlink" href="#for-ilo-based-proliant-servers" title="Link to this heading">¶</a></h2>
<p>Last reviewed: 08/20/2018</p>
<blockquote>
<div><p>The HPE iLO NMI Watchdog driver is a kernel module that provides basic
watchdog functionality and handler for the iLO “Generate NMI to System”
virtual button.</p>
<p>All references to iLO in this document imply it also works on iLO2 and all
subsequent generations.</p>
<p>Watchdog functionality is enabled like any other common watchdog driver. That
is, an application needs to be started that kicks off the watchdog timer. A
basic application exists in tools/testing/selftests/watchdog/ named
watchdog-test.c. Simply compile the C file and kick it off. If the system
gets into a bad state and hangs, the HPE ProLiant iLO timer register will
not be updated in a timely fashion and a hardware system reset (also known as
an Automatic Server Recovery (ASR)) event will occur.</p>
<p>The hpwdt driver also has the following module parameters:</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p>soft_margin</p></td>
<td><p>allows the user to set the watchdog timer value.
Default value is 30 seconds.</p></td>
</tr>
<tr class="row-even"><td><p>timeout</p></td>
<td><p>an alias of soft_margin.</p></td>
</tr>
<tr class="row-odd"><td><p>pretimeout</p></td>
<td><p>allows the user to set the watchdog pretimeout value.
This is the number of seconds before timeout when an
NMI is delivered to the system. Setting the value to
zero disables the pretimeout NMI.
Default value is 9 seconds.</p></td>
</tr>
<tr class="row-even"><td><p>nowayout</p></td>
<td><p>basic watchdog parameter that does not allow the timer to
be restarted or an impending ASR to be escaped.
Default value is set when compiling the kernel. If it is set
to “Y”, then there is no way of disabling the watchdog once
it has been started.</p></td>
</tr>
<tr class="row-odd"><td><p>kdumptimeout</p></td>
<td><p>Minimum timeout in seconds to apply upon receipt of an NMI
before calling panic. (-1) disables the watchdog. When value
is > 0, the timer is reprogrammed with the greater of
value or current timeout value.</p></td>
</tr>
</tbody>
</table>
<dl class="simple">
<dt>NOTE:</dt><dd><p>More information about watchdog drivers in general, including the ioctl
interface to /dev/watchdog can be found in
<a class="reference internal" href="watchdog-api.html"><span class="doc">The Linux Watchdog driver API</span></a> and <a class="reference internal" href="../driver-api/ipmi.html"><span class="doc">The Linux IPMI Driver</span></a></p>
</dd>
</dl>
<p>Due to limitations in the iLO hardware, the NMI pretimeout if enabled,
can only be set to 9 seconds. Attempts to set pretimeout to other
non-zero values will be rounded, possibly to zero. Users should verify
the pretimeout value after attempting to set pretimeout or timeout.</p>
<p>Upon receipt of an NMI from the iLO, the hpwdt driver will initiate a
panic. This is to allow for a crash dump to be collected. It is incumbent
upon the user to have properly configured the system for kdump.</p>
<p>The default Linux kernel behavior upon panic is to print a kernel tombstone
and loop forever. This is generally not what a watchdog user wants.</p>
<dl class="simple">
<dt>For those wishing to learn more please see:</dt><dd><ul class="simple">
<li><p><a class="reference internal" href="../admin-guide/kdump/kdump.html"><span class="doc">Documentation for Kdump - The kexec-based Crash Dumping Solution</span></a></p></li>
<li><p><a class="reference internal" href="../admin-guide/kernel-parameters.html"><span class="doc">The kernel’s command-line parameters</span></a> (panic=)</p></li>
<li><p>Your Linux Distribution specific documentation.</p></li>
</ul>
</dd>
</dl>
<p>If the hpwdt does not receive the NMI associated with an expiring timer,
the iLO will proceed to reset the system at timeout if the timer hasn’t
been updated.</p>
</div></blockquote>
<p>--</p>
<blockquote>
<div><p>The HPE iLO NMI Watchdog Driver and documentation were originally developed
by Tom Mingarelli.</p>
</div></blockquote>
</section>
</section>
</div>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="footer">
©The kernel development community.
|
Powered by <a href="https://www.sphinx-doc.org/">Sphinx 8.1.3</a>
& <a href="https://alabaster.readthedocs.io">Alabaster 0.7.16</a>
|
<a href="../_sources/watchdog/hpwdt.rst.txt"
rel="nofollow">Page source</a>
</div>
</body>
</html>