Created attachment 112775 [details]
Xorg.0.log with backtrace
My desktop system is configured to use a simple zaphod head configuration, first head is dedicated to my monitor, the second head is a TV. The config is bound to an AMD Radeon HD 5430 card.
I'm also operating vga-passthrough VMs by using KVM/qemu on that system.
A second GPU (GeForce GTX 980) is mainly dedicated for this purpose. There are NO related nouveau/NVIDIA kernel and X components (DDX, mesa etc. ) installed.
So far this setup works great.
Now when I install a third GPU, no matter it is an additional NVIDIA based or AMD based GPU, the X Server instance crashes.
(Side note: AMD based GPUs are stubbed out with pci-stub using the kernel command line to make sure those cards are not picked up by X accidentally).
I noticed this behavior only when using a zaphod config, removing any xorg configs everthing is working.
X.Org X Server: 1.15.2
Created attachment 112776 [details]
Attempt to create a more meaningful backtrace with gdb.
Created attachment 112777 [details]
Zaphod head mode xorg.conf file.
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