永远不变的东西，原理
study roadmap:
1.user space:
tizen power manager => suspend/resume or runtime?
android power manager => early suspend / wakelock / suspend/resume / platform sleep
2.kernel:
linux original suspend/resume
linux runtime pm
3.write my own power manager
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1.cpu p-states / c-states
2.linux cpu freq governor
3.cpu architecture， 计算机组成原理
4.os principle
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从头开发一些现有设备的驱动 ：
1. 网卡
2.usb设备，USB摄像头(需要v4l2)
3.串口
4.sd card / emmc
=================================================
1. how to analyze app crash
strace
backtrace
map
coredump
......
indicator-datetime 显示日期的app crash 分析
2.LTTng tracer
http://lwn.net/Articles/491510/
3.gst camera:
http://www.twm-kd.com/linux/webcam-and-linux-gstreamer-tutorial/
http://www.ideasonboard.org/uvc/
http://blog.csdn.net/shenbin1430/article/details/5708345
gstreamer:
http://www.oz9aec.net/index.php/gstreamer/345-a-weekend-with-gstreamer
http://wiki.oz9aec.net/index.php/Gstreamer_Cheat_Sheet
http://www.eisfuchs.info/eisfuchs/gstreamer/
http://lac.linuxaudio.org/2010/download/GStreamerAudioApps.pdf
https://people.gnome.org/~gman/guadec_talks/guadec-gst-app-dev.pdf
https://developer.ridgerun.com/wiki/index.php/Gstreamer_Creating_C_Code_Applications
http://lwn.net/Articles/464270/
http://www.khronos.org/files/openmax/whitepapers/OpenMAX_IL_with_GSstreamer.pdf
http://techslides.com/sample-webm-ogg-and-mp4-video-files-for-html5/
http://www.bigbuckbunny.org/index.php/download/
https://github.com/spk121/burro-engine/wiki/GStreamer-Tutorial-%231:-How-I-Made-a-Beep!
http://mil-oss.org/resources/mil-oss-wg3_gstreamer-for-video-processing-applications_josh-doe.pdf
http://www.twm-kd.com/linux/webcam-and-linux-gstreamer-tutorial/
http://wiki.oz9aec.net/index.php/Gstreamer_Cheat_Sheet#cite_note-gst-doc-1
http://blogs.elphel.com/2009/11/interfacing-elphel-cameras-with-gstreamer-opencv-opengl-and-python-get-profit-of-dsp-or-gpu-based-optimisation-control-camera-settings-from-python-application-or-human-interface-device-hid/
http://noraisin.net/diary/?p=40
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/faq/html/chapter-using.html