Warning: The following steps require a device to be rooted which makes warranty void and can cause bricking of the phone. Proceed at your own risk. There are some complicated details for the procedure.
1. Samsung Galaxy S3 must be rooted
2. Have a kernel with loop support
3. Omega 4.0 ROM is a suggested to be flashed on Galaxy S3
4. USB debugging enabled
1. Download Ubuntu.sh and copy it to the SD card root directory.
2. Launch the Terminal Emulator app and enter the following commands:
3. Message will prompt asking what screen size do you want in pixels. Enter the following:
4. After that the terminal will ask for a password. According to the developer, it is ubuntu. You may need to enter the password twice.
5. Exit the Terminal Emulator app and launch the VNC Viewer app. Enter the following:
6. The VNC Viewer will display the details and you can now tap to the “connect” button.
By following the instruction carefully, the Galaxy S3 will run Ubuntu. Visit the xda original thread for screenshots, questions or comments.