[ubuntu] Blank virtual terminals in Ubuntu 14.04 Dom0 under Xen 4.4 (UEFI)

I have a newly built machine running Ubuntu 14.04. I've been working on getting Xen 4.4 set up on the machine. When I first installled Xen, it was booting via grub, and I was getting an error message "WARNING: no console will be available to OS". Upon boot, tty7 showed MATE display manager just fine (and X worked upon login), but the other virtual terminals all displayed blank black screens. Googling the error message revealed it to be related to booting Xen through Grub on a UEFI system, so I compiled the Xen EFI loader, dropped it into my EFI partition, and set up EFI to load Xen directly on boot. I no longer receive the error message, and the kernel does display some text output on boot (there is no splash screen when booting Xen directly from EFI, which I'm perfectly fine with), but once boot is complete I have the same problem as before: I get graphical output on tty7, but the other virtual terminals are completely blank.

I set up xen.cfg to boot Linux with the following command line:

From this source, I made the wild guess that adding "xencons=xvc console=xvc0 console=tty1" might help, but that has not accomplished anything.

Virtual terminals work just fine in bare Ubuntu without Xen. The machine is using a Radeon R7 260X for the graphics adapter.

Can anyone provide any pointers on this?