[vfio-users] Passing intel_iommu=on in grub causes boot to immediately lock on two different X58 LGA1366 MB.

[A de Beus]

Make sure you have the latest BIOS for that board. Some of the ASUS boards needed an update for IOMMU.

> On May 18, 2016, at 2:28 PM, Alex Williamson <alex.l.williamson at gmail.com> wrote:
> 
> [re-adding vfio-users]
> 
>> On Wed, May 18, 2016 at 1:48 PM, Brian Yglesias <brian at atlanticdigitalsolutions.com> wrote:
>> I've attached with quiet removed (should have done that already).
>> 
>> Nothing jumps out at me, hopefully someone else will see something.
>> 
>> With iommu=pt in lieu of intel_iommu=on the system boots, but no iommu support.  If I append iommu=pt it continues to hard lock.
>> 
>> I've included two images.
>> 
>> It does seem to be somehow iommu related.
>> 
>> I found this post on centos forums:
>> 
>> https://www.centos.org/forums/viewtopic.php?t=46809
>> 
>> That seems to be the same problem with a non-X58 board.  Unfortunately, I don't have the BIOS setting he appears to have used to fix it.
>> 
>> Thanks for all the help thus far.
>> 
>> I'm going to post on Gigabyte forums.  I've seen on both the archlinux forum and the former that ppl have gotten iommu working with this board, which is why I bought it.  Not sure what my problem could be yet.
>> 
> 
> I don't think that centos issue is related, that's a DMA alias issue with broken I/O hardware.  What you're seeing is a hang in qi_submit_sync(), which is an impossible hang according the hardware specs, but comes up a fair bit more often than never.  AIUI, it means that magic, undocumented bits in hardware aren't set the way they should be and you're going to need to hope for a BIOS update, which is all but impossible on a system as old as X58.  Good luck :-\
> 
> Alex
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