Dual boot OS X and Ubuntu on Mac Pro (Late 2013)

1. Make bootable Ubuntu USB disk
  1.1 Download Ubuntu
  1.2 Open Terminal
  1.3 hdiutil convert -format UDRW -o /Users/username/Downloads/ubuntu.img /Users/username/Downloads/ubuntu.iso
  1.4 Change ubuntu.img.dmg to ubuntu.img
  1.5 diskutil unmountDisk /dev/disk1
  1.6 sudo dd if=/Users/username/Downloads/ubuntu.img of=/dev/rdisk1 bs=1m
  1.7 diskutil eject /dev/disk1

2. partition
  2.1 Open Disk Utility
  2.2 Select APPLE SSD SM1024F Media
  2.3 Click Partition
  2.4 Change the size of Macintosh HD and apply

3. Install rEFInd
  3.1 Download rEFInd
  3.2 Extract downloaded zip file
  3.3 Reboot and hold Command+R
  3.4 Utilities -> Terminal
  3.5 cd /Volumes/Macintosh\ HD/Users/username/Downloads/refined
  3.6 ./refind-install

4. Launch rEFInd
  4.1 Shut down
  4.2 Insert Ubuntu USB
  4.3 Restart

5. Launch Ubuntu Live
  5.1 Select penguin icon in rEFInd
  5.2 Move highlight to "Try Ubuntu without install"
  5.3 Press "e"
  5.4 Insert "nomodeset radeon.audio=1" between "splash" and "--"
  5.5 Press "F10"

6. Install Ubuntu
  6.1 Click install icon
  6.2

References
http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx
http://www.howtogeek.com/187410/how-to-install-and-dual-boot-linux-on-a-mac/
http://www.rodsbooks.com/refind/sip.html
http://samiux.blogspot.com/2015/02/howto-ubuntu-1404-lts-desktop-on-mac.html