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

Wed Jan 30 04:52:18 UTC 2013
Gordon Messmer <yinyang at eburg.com>

On 01/29/2013 01:16 PM, Nils Caspar wrote:
> Everything works so far, but when I add intel_iommu=on to the kernel
> line of my grub.conf, Dracut gives my a kernel panic while booting. I
> added "rdshell" to the command line and extracted the boot messages
> via dmesg (http://nilscaspar.ch/centos-dmesg.log).

Similar behavior has been diagnosed as a hardware bug:

Boot the system with the IOMMU off and find out what PCI device is at 
05:01.0 using lspci.  Assuming that it's not critical, try disabling or 
removing that component.