Our AMIGA one X1000 doesn't boot with the irq source code from the kernel 4.2. I had to downgrade this source code to the kernel 4.1 irq source code last week. After the downgrade, our AMIGA one X1000 booted without any problems with the old kernel 4.1 irq source code. The kernel developers updated the kernel 4.2 irq source code yesterday.
https://git.kernel.org/cgit/linux/kerne ... bc9dcffad4
Therefore I compiled the RC2 without downgrading the irq source code today. Unfortunately the RC2 of kernel 4.2 doesn't boot with the updated kernel 4.2 irq source code.

I downgraded the irq source code to the kernel 4.1 (4.1.2) irq source code again. After then it boots without any problems.
Download: vmlinux-4.2-rc2-AMIGA_one_X1000.tar.bz2
New:
Linux 4.2-rc2 Kernel Released, Just Another Update
Release announcement by Linus Torvalds
By the way, I updated my ubuntu MATE 15.04 today.
Unfortunately the issues are still exists. You have to install some old Xorg packages to get a working X11. The ubuntu MATE 15.04 desktop has some problems with systemd. You have to install upstart to get a full functional ubuntu MATE 15.04 desktop. If you want to use 3D acceleration you will have to install the unofficial Mesa. I created a package with all debs and Mesa libs for a downgrade four months ago.
Download: Xorg_and_unofficial_Mesa_for_ubuntu_MATE_15.04_AMIGA_one_X1000.tar.gz
But ... It looks like the xserver-xorg-core 1.17.2-1 fixed the xorg issues on PowerPC machines! This should come downstream to Ubuntu soon.
Rgds,
Christian