[Libreboot] message during boot: "DMAR: Failed to map dmar2"

[Bruno Dantas]

I am running Parabola on a Libreboot T400 that I purchased from Ministry of 
Freedom. I have not made any changes to Libreboot.

Every time I boot into my Parabola installation, I see this message: "DMAR: 
Failed to map dmar2". I booted into Parabola's live CD just to see what would 
happen, and the same message scrolls by during the boot process. Once Parabola 
is fully booted and I'm at the desktop (mine or live CD's), everything seems to 
be working fine.

Here are the relevant lines from dmesg: http://pastebin.com/Fw7NH6tn

What does this DMAR failure mean? Is it fixable? If not, is there a way to make 
the error stop showing up during boot? I read somewhere that adding iommu=soft 
to the kernel boot parameters makes the error go away, but that didn't have any 
effect.

Thanks,
Bruno