I started fiddling some more. And also took a look at this topic: Play games in Windows on Linux! PCI passthrough quick guide
find /sys/kernel/iommu_groups/ -type l yielded iommu group results. With one that is my gpu. So thats a first step.
Then i changed the /etc/modules (and updated initramfs) file and did a reboot. Then tried to create a new VM in virt-manager.
When doing the steps exactly as described in the linked topic I got the vm to boot up but unable to boot from the cd.
Then I created a vm as described in the first two tutorials I linked in my initial post and it seems I can install it the normal way.
One thing i noticed is that it keeps “typing” zeros? Is that a bug or something? I luckily could create a new partition in the instaler and go on with the installation.
So given this, is it really mandatory to have those dmesg commands giving results?
And is the intremap still needed?