Comment 12 for bug 1422675

The problem is not PAE, the problem is that the kernel parameters parser was changed as a result of the systemd debug params controversy.

You need to repeat the 'forcepae' twice in the linux kernel parameters, before and after the -- i.e.:

        linux ... forcepae -- forcepae

Kernel patch that changed the previous behaviour was:

        commit 51e158c
        Author: Rusty Russell <email address hidden>
        Date: Mon Apr 28 11:34:33 2014 +0930
            param: hand arguments after -- straight to init

        The kernel parses parameters from the kernel command line up to "--";
        if it doesn't recognize a parameter and it doesn't contain a '.', the
        parameter gets passed to init: parameters with '=' go into init's
        environment, others are passed as command line arguments to init.
        Everything after "--" is passed as an argument to init.

With "forcepae -- forcepae" I did a full install of the Vivid ISO link above. It worked ok.

(There was a non-related bug, Ubuntu/grub puts "vt.handoff=7" in grub.cfg which causes a black screen on boot - looks like bug #913731 or some related regression).