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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>medium
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Please add CPU and memory hotplug udev rules"
href="https://bugs.freedesktop.org/show_bug.cgi?id=78478">78478</a>
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<th>Assignee</th>
<td>systemd-bugs@lists.freedesktop.org
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<th>Summary</th>
<td>Please add CPU and memory hotplug udev rules
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<th>QA Contact</th>
<td>systemd-bugs@lists.freedesktop.org
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<th>Severity</th>
<td>normal
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>All
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<th>Reporter</th>
<td>benjamin.drung@profitbricks.com
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<th>Hardware</th>
<td>Other
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Component</th>
<td>general
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<th>Product</th>
<td>systemd
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<p>
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<pre>Hi,
please add udev rules to enable hotplugged CPUs and memory. I propose following
two rules:
ACTION=="add", SUBSYSTEM=="cpu", ATTR{online}=="0", ATTR{online}="1"
ACTION=="add", SUBSYSTEM=="memory", ATTR{state}=="offline",
ATTR{state}="online"
These rules are tested (without the ATTR online/state checks) on Debian
7/testing, Fedora 19/20/21, and Ubuntu 12.04/13.10/14.04.
Some distributions already ship CPU and memory hotplug rules. openSUSE 13.1 has
80-hotplug-cpu-mem.rules:
SUBSYSTEM=="cpu", ACTION=="add", TEST=="online", ATTR{online}=="0",
ATTR{online}="1"
SUBSYSTEM=="memory", ACTION=="add", TEST=="state", ATTR{state}=="offline",
ATTR{state}="online"
CentOS 6 modified the acpi_memhotplug kernel module to automatically online
memory (configurable with CONFIG_ACPI_HOTPLUG_MEMORY_AUTO_ONLINE). This patch
is not mainlined (yet). They ship one rule for CPU hotplugging in
/lib/udev/rules.d/40-redhat.rules:
ACTION=="add", KERNEL=="cpu[0-9]*", RUN+="/bin/bash -c 'echo 1 >
/sys/devices/system/cpu/%k/online'"</pre>
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