Description of problem:

Since kernel upgrade machine freezes after Fedora progress bar before login.  Found DMA issue.  Workaround is kernel option iommu=soft.  For a newbie this would be a show stopper for using this version Linux on this big iron.

Version-Release number of selected component (if applicable):

kernel.x86_64 2.6.32.9-67.fc12

How reproducible:

100%

Steps to Reproduce:
1. Software Update to kernel 2.6.32.9-67.fc12, from 2.6.31.12-174.2.22.fc12, which was working.
2. Reboot.
  
Actual results:

Soon after initial Fedora progress bar goes to black screen, no login.

ssh in from other machine shows dmesg keeps repeating

DRHD: handling fault status reg 2
DMAR:[DMA Read] Request device [01:00.0] fault addr 215da0000
DMAR:[fault reason 01] Present bit in root entry is clear

Expected results:

Log in normally and use computer.

Additional info:

The akmod-nvidia.x86_64 195.36.08-1.fc12 that is installed works fine with kernel 2.6.31.12-174.2.22.fc12.

Workaround is on relevant kernel line, i.e. for 2.6.32.9-67.fc12, to append iommu=soft