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Powerd is one of the primary daemons that is started when webOS boots. It is responsible for monitoring battery parameters like temperature, current, voltage and other inputs, and making decisions about battery charging. It interfaces with the underlying hardware using the Nyx client library, talking to the battery and charger modules for the platform. At the same time it exposes the battery and charging information to the upper layers through the Luna Service Bus. Powerd also has the capability to run the necessary CTIA checks for temperature limits on the platform.

How to Build on Linux


Below are the tools and libraries (and their minimum versions) required to build powerd:

  • cmake 2.6
  • gcc 4.3
  • glib-2.0 2.16.6
  • make (any version)
  • openwebos/cjson 1.8.0
  • openwebos/luna-service2 3.0.0
  • openwebos/nyx-lib 2.0.0 RC 2
  • pkg-config 0.22


Once you have downloaded the source, execute the following to build it:

$ mkdir BUILD
$ cd BUILD
$ cmake ..
$ make
$ sudo make install

The header files will be installed under


the libraries and pkg-config file under


the daemon under


the default preferences file under


and the upstart script under


You can install it elsewhere by supplying a value for CMAKE_INSTALL_PREFIX when invoking cmake. For example:

$ cmake -D CMAKE_INSTALL_PREFIX:STRING=$HOME/projects/openwebos ..
$ make
$ make install

will install the files in subdirectories of $HOME/projects/openwebos instead of subdirectories of /usr/local.

Specifying CMAKE_INSTALL_PREFIX also causes the pkg-config files under it to be used to find headers and libraries. To have pkg-config look in a different tree, set the environment variable PKG_CONFIG_PATH to the path to its lib/pkgconfig subdirectory.


From the directory where you originally ran make install, invoke:

$ sudo xargs rm < install_manifest.txt

Generating documentation

The tools required to generate the documentation are:

  • doxygen 1.6.3
  • graphviz 2.20.2

Once you have run cmake, execute the following to generate the documentation:

$ make docs

To view the generated HTML documentation, point your browser to


Linking against libpowerd

If your system has pkg-config then you can just add this to your makefile:

CFLAGS += $(shell pkg-config --cflags powerd)
LDFLAGS += $(shell pkg-config --libs powerd)

Copyright and License Information

Unless otherwise specified, all content, including all source code files and documentation files in this repository are:

Copyright (c) 2007-2012 Hewlett-Packard Development Company, L.P.

Unless otherwise specified or set forth in the NOTICE file, all content, including all source code files and documentation files in this repository are: Licensed under the Apache License, Version 2.0 (the "License"); you may not use this content except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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