How to install Ubuntu 17.04 on Dell XPS 15 9550

I had some trouble installing Ubuntu 17.04 to dual-boot with Windows 10 on my Dell XPS 15 9550, so documenting here in case it helps others...

Once I got Ubuntu installed, it runs well. I'm using the NVIDIA proprietary driver, and I've had no major issues with hardware yet so far.

Most of the installation hurdles for me were caused by Ubuntu not being able to see the disk drive while it was operating in Raid mode, and UEFI/Secure Boot seemed to block the install somehow.

The trick to getting past these hurdles was to set Windows to boot into Safe Mode and then switch the disk drive to AHCI and disable UEFI in the BIOS before booting back into Windows in Safe Mode, and then switching Windows back to non-Safe Mode.

I found rcasero's notes on installing Ubuntu on Dell XPS 15 9560 useful.

Detailed steps to install...

1. (If your Windows partition is encrypted, print out a copy of your BitLocker key. You'll need to enter this on boot after changing anything in your BIOS.
2. Boot into Windows 10.
3. I also needed to resize my main Windows partition from inside Windows; the Ubuntu installer seemed unable to cope with resizing my encrypted Windows partition for some reason. You can resize your main Windows partition using Windows' "Create or edit Disk Partitions" tool.
4. Configure Windows to boot into safe mode: Press Win+R and run msconfig.exe > Boot > Safe Mode. Reboot.
5. Press the F12 key while the BIOS splash screen comes up. Just repeatedly pressing it while the machine is booting seems to be the most reliable tactic.
6. In the BIOS menu, BIOS Setup > System Configuration > SATA Operation, change "RAID On" to "AHCI".
7. In the BIOS menu, disable Secure Boot.
8. Reboot into Windows. You'll need to enter your BitLocker key to unlock the drive since the BIOS changed. Windows will boot into Safe Mode. If you don't have your Windows install set to boot into Safe Mode, you'll get a BSOD.
9. Once you've booted into Windows Safe Mode, you can configure Windows to boot in normal (non-Safe Mode) with msconfig.exe > Boot > Safe Mode again.
10. Reboot with your Ubuntu USB Live Disk inserted, and press F12 while booting to select to boot from the Live USB disk.
11. The rest of the install Just Worked.
12. Once you've installed Ubuntu, for better reliability and performance, enable the proprietary GPU drivers, in System Settings > Software and Updates > Additional Drivers. I enabled the NVIDIA and Intel drivers.
13. I've found the touchpad often registers clicks while I'm typing. Turning off System Settings > Mouse and Touchpad > "Tap to click" fixed this and gives pretty good touchpad behaviour.
14. Firefox by default has its hardware accelerated layers disabled, but force-enabling it seems to work fine. Open "about:config" in Firefox, and toggle "layers.acceleration.force-enabled" to true. Restart Firefox.