title: Different functionality between ARM SMMU and x86 IOMMU?
body: <p>I have survey some I/O virtualization things.
  And I found that IOMMU is a key hardware component for hardware-assisted I/O virtaulization.</p>
  
  <p>How about the ARM SMMU?
  Is there any difference between ARM SMMU and x86 IOMMU?</p>
  
  <p>Thanks!</p>