UNRAID kernel: DMAR: DRHD: handling fault status reg 40


Recommended Posts

Whenever I run my Windows 7 or Windows 10 VM with my AMD RX 560 card passed thru the system runs for an hour or two and then the entire UNRAID system halts with the above error.


I have done a number of google searches and I can not find what an error 40 means.


Can anyone help?


Solutions for other DMAR: DRHD errors is to add an line in the Kernel parameter intel_iommu=off




Link to comment



I was determined to fix this issue:

1) I downgrade the AMD drivers - NO CHANGE

2) Removed the AMD driver and reverted back to the stock Windows 10 driver - NO CHANGE

2) I moved the card to  a different slot- NO CHANGE

3) I removed the card and replaced it with an older AMD card with support for the same drivers - FIXED


I also put the card in a standalone Windows 10 machine (as I thought maybe there was a defect in the card) and it has run stable for over 24 hours now. I think the card is good.


If you are using a AMD RX 5xx card via pass-thru to a Win 7 or Win10 machine please post and let me know if you have been successful. I know there have been alot of issues with the AMD RX cards with pass thru. Before I buy another one I want to make sure I am not going to have issues. 



Link to comment
  • 2 years later...
  • 3 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.