title: PX4/Firmware make error
body: <p>Question： When I run <code>make px4fmu-v2_default</code>， I get this：</p>
  
  <pre class="lang-none prettyprint-override"><code>rootroot:~/Firmware$ make px4fmu-v2_default
  
  Makefile:44: Not a valid CMake version or CMake not installed.
  Makefile:45: On Ubuntu, install or upgrade via:
  Makefile:46: 
  Makefile:47: 3rd party PPA:
  Makefile:48: sudo add-apt-repository ppa:george-edison55/cmake-3.x -y
  Makefile:49: sudo apt-get update
  Makefile:50: sudo apt-get install cmake
  Makefile:51: 
  Makefile:52: Official website:
  Makefile:53: wget https://cmake.org/files/v3.3/cmake-3.3.2-Linux-x86_64.sh
  Makefile:54: chmod +x cmake-3.3.2-Linux-x86_64.sh
  Makefile:55: sudo mkdir /opt/cmake-3.3.2
  Makefile:56: sudo ./cmake-3.3.2-Linux-x86_64.sh --prefix=/opt/cmake-3.3.2 --exclude-subdir
  Makefile:57: export PATH=/opt/cmake-3.3.2/bin:$PATH
  Makefile:58: 
  Makefile:59: *** Fatal。 停止。
  </code></pre>
  
  <p>My CMAKE version</p>
  
  <pre class="lang-none prettyprint-override"><code>root@root：~/Firmware$ cmake --version
  
  cmake version 3.0.2
  
  CMake suite maintained and supported by Kitware (kitware.com/cmake).
  </code></pre>
  
  <p>Why？ </p>