Comment 9 for bug 35788

I had the very same problem on an IBM x326m 7969-67Y, which is a dual opteron 275.

Removing the Remote Supervisor Adapter II fixed the boot problem. The card is what IBM calls a Baseboard Management Controller, an MS-9549 PCI card. However, then fan controll stopped working :-(

I seem to be having some problems with iommu too, and when enabling earlyprintk=vga it stops right after having complained about not having an aperture.