Talk:VTd HowTo

• --John Poole Dec 27, 2023: As of December 27, 2023, this page has "VT-d Pass-Through is a technique to give a domU exclusive access to a PCI function using the IOMMU provided by VT-d." VT-d should be defined at it first use, or at least a link to the term's definition. I found this definition:

   At Intel, VT-d means virtualization for technology direct I/O access.
   

Source: https://www.kensington.com/news/docking-connectivity-blog/what-is-intel-vt-d-dma-protection/

• --Lynx 3 Aug 17 : Asus Engineer recently told me that the ASUS P8Z77-M PRO does not support VT-d. Disappointing really, since this motherboard is supposed to support Intel chips that do support it, such as the i5-3570. I've updated the listing accordingly.

• --AlphaC 9 June : Asrock recently added iommu support via bios update on all A75 A55 motherboards, I have a A75Pro4-M, after upgrading IOMMU was enabled, not tried with xen yet, this the line I get from dmesg:

[ 0.518494] AMD-Vi: Enabling IOMMU at 0000:00:00.2 cap 0x40 extended features: PreF PPR GT IA

• --1Samildanach 05:03, 7 June 2012 (UTC) : I have attempted to contact a few motherboard manufacturers directly. It has been a week and ASRock has not gotten back to me (it was hard to find an email address, too). Asus has very limited contact options, and the person I talked to by phone was unable to find information on VT-d. MSI and Gigabyte, however, were quite prompt and helpful. Here are the boards they listed:

MSI: Z77A-GD80, Z77A-GD65, Z77A-GD55, Z77A-G45, and Z77A-G43     
        
Gigabyte: GA-X79-UD5 (rev. 1.0), GA-X79-UD7 (rev. 1.0) and GA-Z77X-D3H (rev. 1.0)

• --Lars.kurth 08:40, 7 June 2012 (UTC) : I am quite happy for you to update the main page with the information you found, unless you are looking for somebody to do a quick sanity check. Thank you for the efforts.

• --1Samildanach 06:59, 13 June 2012 (UTC) : Done. Feel free to change the wording if you can think of a clearer way of putting it. May also be worth contacting them again in six months or so, to get information on any boards released in that time... though I might not remember to do so.

• --Przemoc86 19:31, 3 February 2013 (UTC) : Regarding ASRock Z77 Extreme4 & Extreme6: I am planning on buying one of these mobos so I did some research on the Internet and I think the warning stated here about the recent BIOSes cutting down vt-d functionality may be wrong, but I am not sure yet. On the Extreme6 Download page we can read in relevant BIOSes descriptions:

  Modify VT-d Capability will be unsupported after flashing BIOS P2.30.

  which may be read as "turning off possibility to change its enable state" (such sites are known for pretty bad English). I know that ASRock America Support wrote about Extreme4 to Chetyre user from overclock.net forum that:

  After you update the BIOS with the 2.70 the VT-D not longer works

  but it's not a good source of knowledge, because front-line support people are often quite incompetent. (Well, there are naming mistakes in BIOSes too, like I showed once, thus double or triple checking is almost always required.)
  Moreover, there is at least one source stating that vt-d still works after upgrade. abel user from tom's hardware forum responded to question about 2.30 and 2.40:

  I ran across the 2.30 BIOS after I updated while reinstalling Win7 64. Here's what I found: the VTd still worked, it just did not show up in the BIOS pages as a choice (along with VTi). I can confirm this, because I had my discrete video card connected directly to my monitor at the same time I had VirtuMVP enabled. If VTd didn't work, I would have had no monitor image at all. BIOS 2.40 fixed the user interface on the BIOS page, that's all. In sum, the functionality in 2.30 was always there.

  I can agree it's not explicitly stated here whether abel used 2.40 in the end, so I'll try to contact him to confirm that.
• --Przemoc86 00:50, 16 February 2013 (UTC): I received the first confirmation that ASRock Z77 Extreme6 supports VT-d in BIOS v2.40. Quoting Keroberos from his blog http://mo.kerosoft.com/0198:

  Initially, the BIOS was P2.30 with VT-d capability "Unsupported" when I bought Z77 Extreme6. The default "VT-d" value was "Disabled" as you pointed out. Above first capture image is "VT-d Enabled" because I have enabled it. Of course, it didn't work VT-d capability completely.
  
  After upgrading BIOS to P2.40, all setting parameters had been reset to initial state. The second image was captured at this moment. Then I switched "VT-d" settings on, and it works perfectly. As an evidence, I added one more capture image with working VT-d capability in VMware ESXi.

BIOS Version

First off, thank you, everyone for how much you work with getting this amazing part of Xen working and accessible to the relatively uninitiated. As you may know, this is becoming an authoritative page on what boards work well with VT-d and PCI/VGA passthroughs. Thus, do you think it possible to have the people who logged the working motherboards to also put their BIOS versions? I know as a first-time user, it would have saved me buying/returning two motherboards and also spending hours downgrading BIOSes and whatnot.

Also, are there any objections to putting a list of boards known not to work as well? I could at least contribute my information which I've learned to the community.

Cheers! -b1tst0rm