[CentOS] intel_iommu=on => No root device found

Wed Jan 30 19:51:58 UTC 2013
Gordon Messmer <yinyang at eburg.com>

On 01/29/2013 11:35 PM, Nils Caspar wrote:
> I can not see a 05:01.0 using lspci. There is however 05:0e.0, which
> is the RAID controller (Adaptec RAID 3405). It's kind of a critical
> component, so I can not disable it. ;) Does this mean, it's
> impossible to make IOMMU work on this machine?

Try booting the system without intel_iommu=on, but with the IOMMU 
enabled in the bios.  Something has to be at 05:01.0.  Do you see any 
Ricoh devices anywhere in lspci output?