IOMMU passthrough by default


Linux Kernel Configuration
└─>Device Drivers
└─>IOMMU Hardware Support
└─>IOMMU passthrough by default
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Enable passthrough by default, removing the need to pass in
iommu.passthrough=on or iommu=pt through command line. If this
is enabled, you can still disable with iommu.passthrough=off
or iommu=nopt depending on the architecture.

If unsure, say N here.