(setup cross project)
File -> New -> C Project
"C Project" window
    Project name: hello
    Project type: Hello World ANSI C Project
    Toolchains: Cross GCC
"Basic Settings" window
    (author, copyright, ...)
"Select Configurations" window
    Debug, Release
"Cross GCC Command" window
    Cross compiler prefix: arm-linux-gnueabihf-
    Cross compiler path: /opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin

(modify existing project)
Project -> Properties
C/C++ Build -> Settings

(setup debug)
Run -> Debug Configurations
"Create, manage, and run configurations" window
    select "C/C++ Remote Application" and click "New" icon
"Main" tab
    Connection: New...
"Create a new connection" window
    Connection type: SSH
"New Connection" window
    Connection name: qemu-arm
    Host: localhost
    User: root
    Password based authentication
    Password: root
    Advanced
        Port: 2222
        Use login shell
        Login shell command: /bin/sh -c '{0}'
"Main" tab
    Remote Abolsute File Path for C/C++ Application: /hello
"Debugger" tab
    "Main" sub-tab
        GDB debugger: /opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gdb
    "Gdbserver Settings" sub-tab
        Port number: 12345