Re: [BUG REPORT] 260.19.36 64-bit Linux driver conflicts with AMD 890FX IOMMU
The point isn't that it is not widely used, its that it is questionable that you're even using the feature. (You don't really need it when running a pair of 580s in SLI, that's for sure) I don't think VMWare is using it either, unless you have some bleeding edge version, ESX/ESXi 4 or above, or some other enterprise version.
I have a TYAN S7025 (Dual Processor/NUMA) board with Intel's IOMMU support, and there are no issues with the 260.19.* drivers.
I'm not saying that your issue isn't a bug or that you should not be doing something you are. I'm saying you should make your use case more clear.