SR-IOV issue

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Spelac

New Member
Oct 7, 2020
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Hi guys,

I'm having issues with my new home virtualization host. These are the (relevant) specs:
CPU: i3 10100
MB: H410M-ITX/ac
NIC: I350-T4V2

It's all running on Server 2019 Datacentar edition

When i run Get-Netadaptersriov in power shell i get MissingAcs under SriovSupport. All releveant BIOS options are enabled. ASRock support suggested i should enable "Above 4G Decoding" setting in BIOS. It didn't help. I've tried all kinds of combinations of pcie-related settings in BIOS but no success so far...
So, my question is - is SR-IOV even possible on a mainstream HW such as above? Is it a limitation of a CPU, motherboard or both perhaps? I'm really confused with SR-IOV option in BIOS if the motherboard doesn't support it. If it's up to a CPU that makes sense then.
ASRock support also suggested i shoould switch to Windows 10 because they don't officially support Server 2019. That doesn't really sound like it could help. But I'm willing to try anything. It's not like SR-IOV is totally necessary but i'd like to give it a try. It's just bothering me, to be honest... :)

Thanks for any feedback/thoughts on this

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i386

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Mar 18, 2016
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Dreece

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Jan 22, 2019
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A budget consumer off-the-shelf ITX board, it is 100% the motherboard, Asrock have simply not geared that board for server usage. Sometimes manufacturers just throw in a tweaked bios built-upon an existing base which freely brings all the features through, and in many cases even giving options in the BIOS to enable or disable SRIOV.

If you don't see any options in the bios relative to SRIOV, 9 times out of 10 it means the board's bios is lacking the control code for it.

Good luck getting Asrock to release a new bios with the feature, both Asus and Asrock (two faces of the same company), are a royal butt-ache to deal with when it comes to the bios... I recall at one point rumours were flying around that they only had one bios guru working for them for ALL their boards!!!
 
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Spelac

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Oct 7, 2020
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The thing is - apart from ACS settings there seems to be everything i need in BIOS to make SR-IOV working
ASRock support insist on me to switch to windows 10. I seriously doubt that would make SR-IOV work. If it's not working on Server 2019 why would it work on win 10? It just bothers me that the option is there in BIOS and i can't really use it.
 
Net-Runner

Net-Runner

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Feb 25, 2016
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SR-IOV is not available on Windows 10, as far as I know. I have configure it successfully on Windows Server 2019 on Dell R640 servers with Mellanox CX5 NICs. I think the issue you are facing is related to the MoBo.
 
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Spelac

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Oct 7, 2020
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I've been going back and forth with ASRock support. They are clueless as to if this board actually supports SR-IOV or not. I had a look at another itx board for socket 1200. This time it was Asus. Their support were very clear - no, we don't support SR-IOV and that's it.
Is there any other itx board with this socket that actually supports SR-IOV?
 
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kapone

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May 23, 2015
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@Spelac - It is most likely a combination of your motherboard and CPU. You have a "consumer" level platform/cpu that you're trying to use for non-consumer type stuff. :)

CPU - I tried to look for PCI-E ACS SUPPORT in the specifications for your CPU, but I couldn't find it. The chipset (410M) specifications do mention PCIE ACS support, but not the CPU.

Motherboard - Even if the chipset supports PCI-E ACS (it looks like it does), Asrock may not have implemented it correctly. However, I somewhat doubt this. Asrock is fairly mature at this stage and if it's there in the BIOS screens, it is most likely implemented correctly.

My .02 would be to find a different CPU/motherboard combo.
 
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Spelac

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Oct 7, 2020
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Thanks @Net-Runner - that supermicro board seems great in all aspects bar one - only has 2 sata ports. Luckily there's m.2 slot so that helps a bit. Also, it's great that it supports W-1200 Xeons. But there are only a few with TDP under 65 which is the highest supported on the board. But this really got me thinking. I might replace my current MBO with this one and see if it helps. If it doesn't I'll just have to buy a new Xeon then (my wife's gonna be thrilled).
And another huge plus with this board is that it's probably fully supported by ESXi. I'm currently running all my stuff on Server 2019 because i have no HW monitoring available on ESXi.

@kapone - that's exactly what bothers me - everything is so unclear.

Anyway, thanks for the help guys :)
 
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Net-Runner

Net-Runner

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Feb 25, 2016
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Good luck with your project :) Not exactly the case, but I've had a chance to test SR-IOV on Supermicro X10DRH servers running Windows Server 2019. Everything worked as it should.
 
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zir_blazer

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Dec 5, 2016
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Sadly, I arrived too late for this one.

Consumer Intel Processors does NOT support ACS on the Processor integrated PCIe Controller. This also applies for the Xeon E3 line, so anything using the consumer Sockets is a big no-no. I'm not sure if the latest Socket supports it or not, though, at least until the 8C Coffee Lake (9000 generation) they didn't. However, the Chipsets do support ACS, so you may be able to get SR-IOV working if using those slots.
You will notice the lack of ACS mostly in Linux if using QEMU PCI Passthrough, cause in Motherboards that do PCIe Bifurcation of the Processor PCIe Controller to get two or three slots (8x/8x or 8x/4x/4x), you always get them into the same IOMMU Group. SR-IOV partially relies on ACS for isolation (You CAN create Virtual Functions but no sane Hypervisor will let you passthrough them without ACS cause there is no isolation, so it is insecure by nature), which is why you will never see it working on such platforms. It may be possible that if using Linux and QEMU-VFIO, you can use the infamous ACS patch to assign VFs even with no Hardware ACS isolation.
 
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