Hi, > I think i might have solve it. > > For some reason grub2-mkconfig doesnt work. (Have no idea why) Is this on CentOS 7? Well, yes, I remember that it didn't work for me when I installed new servers one or two years ago, that was with CentOS 7 and they were my first EFI installs. > > I manage to solve it with grubby. > > sudo grubby --args="intel_iommu=on" --update-kernel=ALL > > For some reason it works. I dont know if it works if my kernel gets > upgraded. I have restored the original configs after messing with grub2-mkconfig and only used kernel installs to further modify grub config. That way it has always worked for me. And I was a bis scared by the whole EFI, grub2 and everything around it because I felt I don't really understand how it all interacts in detail. Regards, Simon