So, in reference to this earlier question, which I can't comment on:
I am trying to PXE boot Ubuntu 16.04 on new Dell hardware (R220, R230, R330) and I find that drives set to AHCI mode are not detected. Running 'lspci' in a console window (alt-f2) during the install shows the SATA controller, but parted_devices in the same shell doesn't list any disks. I have to go back to IDE mode in order to get things to work.
Does anyone have any ideas about this? I filed this bug:
https://bugs.launchpad.net/ubuntu/+source/pxe/+bug/1571762
but who knows if and when that will ever be looked at.