ITX Motherboard with IOMMU Separation (no acs)

[jmcguire525]

Can anyone recommend a good itx board that can easily do gpu passthrough without acs override?

[testdasi]

26 minutes ago, jmcguire525 said:

Can anyone recommend a good itx board that can easily do gpu passthrough without acs override?

Typically the primary GPU slot is on its own IOMMU group. ITX mobo has so many unused lanes that it requires effort to have something share the same group with the primary GPU slot, which is the only slot.

[jmcguire525]

4 hours ago, testdasi said:

Typically the primary GPU slot is on its own IOMMU group. ITX mobo has so many unused lanes that it requires effort to have something share the same group with the primary GPU slot, which is the only slot.

Unfortunately the one I have laying around is an exception to that, and its a decent asrock mb

[testdasi]

3 hours ago, jmcguire525 said:

Unfortunately the one I have laying around is an exception to that, and its a decent asrock mb

Perhaps my British sarcasm didn't come through as well as I thought. You asked a generic question with little details and hence I replied with a generic answer with little details.

 

What model is your mobo? How old is it? Did you turn on IOMMU in the BIOS? What CPU are you looking to use? What is your budget? What other hardware you have?

[jmcguire525]

On 11/29/2019 at 12:41 PM, testdasi said:

Perhaps my British sarcasm didn't come through as well as I thought. You asked a generic question with little details and hence I replied with a generic answer with little details.

 

What model is your mobo? How old is it? Did you turn on IOMMU in the BIOS? What CPU are you looking to use? What is your budget? What other hardware you have?

 

I've looked at the IOMMU groups with 2 intel motherboards (EVGA Stinger Z170 and ASRock Z270M-ITX) both have the GPU and PCI bridge in the same group.

 

Right now I'm considering a Ryzen ITX build, 3600 with Asus STRIX B450-I or ASRock Fatal1ty B450.  I do not know what the grouping for those boards are.  

 

If the PCI bridge is in a group with only the GPU does it require the ACS override?  Any idea what the IOMMU groupings are for the Ryzen boards I'm looking at?

[Endy]

IOMMU group 1:	[8086:1901] 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) (rev 05)
[10de:1b81] 01:00.0 VGA compatible controller: NVIDIA Corporation GP104 [GeForce GTX 1070] (rev a1)
[10de:10f0] 01:00.1 Audio device: NVIDIA Corporation GP104 High Definition Audio Controller (rev a1)

This is what mine looks like on a Gigabyte Z170. I have had no problems passing through my graphics card without the need for the ACS override.

[testdasi]

19 hours ago, jmcguire525 said:

 

I've looked at the IOMMU groups with 2 intel motherboards (EVGA Stinger Z170 and ASRock Z270M-ITX) both have the GPU and PCI bridge in the same group.

 

Right now I'm considering a Ryzen ITX build, 3600 with Asus STRIX B450-I or ASRock Fatal1ty B450.  I do not know what the grouping for those boards are.  

 

If the PCI bridge is in a group with only the GPU does it require the ACS override?  Any idea what the IOMMU groupings are for the Ryzen boards I'm looking at?

For PCIe pass-through purposes, you can ignore the bridge existence.  

So in your case, group 1 only has your GPU (and the associated HDMI audio) so can be passed through fine.

 

[jmcguire525]

54 minutes ago, testdasi said:

For PCIe pass-through purposes, you can ignore the bridge existence.  

So in your case, group 1 only has your GPU (and the associated HDMI audio) so can be passed through fine.

 

 

Thanks for the info, in my defense I did read up on this before assuming it needed further separation and this post made me believe the bridge would require acs.  Knowing I don't saves me from buying additional hardware!

[testdasi]

3 hours ago, jmcguire525 said:

Thanks for the info, in my defense I did read up on this before assuming it needed further separation and this post made me believe the bridge would require acs.  Knowing I don't saves me from buying additional hardware!

I posted correction to the other topic too. Thanks for flagging it.