The Broadwell-DE Intel Xeon D-1500 series and SR-IOV

Intel SR-IOV Diagram
Intel SR-IOV Diagram

One hot topic in the STH forums has been that of the Intel Xeon D-1500 series’ support for SR-IOV. We have some updates to share on support in the Intel Xeon D-1500 series given the new chips’ release earlier this week.

What is SR-IOV?

SR-IOV is away to have a Single Root Function (e.g. an Ethernet Port) appear to be multiple separate physical devices. This is useful for virtualization because one can reduce virtualization overhead using a single port rather than adding ports and assigning them to each VM. A useful case here is adding 10GbE to a server than having the NIC shared with multiple VMs.

Here is a good overview paper from Intel on SR-IOV if you are looking for a deeper explanation. If you just want the diagram of what is going on, here is a good one from that paper:

Intel SR-IOV Diagram
Intel SR-IOV Diagram

Is SR-IOV absolutely necessary for virtualization? No. It is a PCI-SIG standard technology to accelerate virtual machine networking.

Intel Xeon D-1540 and Xeon D-1520 Support for SR-IOV

For those that may have missed this in the forums, we did get confirmation from Intel that SR-IOV was indeed not supported by the Intel Xeon D-1540 and D-1520 launch SKUs. Here is the slide we got from Intel for the Broadwell-DE launch. See the SR-IOV support under Optimized for Virtualization.” It is also in the block diagram on the right hand of the slide.

Intel Broadwell-DE Integrated 10GbE
Intel Broadwell-DE Integrated 10GbE

We sent a note to Intel after hearing rumors that Broadwell-DE SR-IOV support was not working. We sent the following to Intel for confirmation:

I heard from a few sources that VT-d or SR-IOV pass-through of the Xeon D’s 10Gb NICs is not possible at this time. I just wanted to confirm this is indeed the case.

and received the following response:

Hi Patrick,

To follow up below, SR-IOV is not enabled in the Intel® Xeon® Processor D-1520 and D1540 products that Intel announced earlier this year.(sic)

With the release of 8 new Intel Xeon D-1500 parts yesterday, we wanted to see if the status has changed.

New Intel Xeon D-1500 series support for SR-IOV

On 9 November 2015 Intel released eight new Intel Xeon D-1500 series SKUs. The primary focus was on on the storage and networking segments. Since SR-IOV was featured prominently in the release materials for Broadwell-DE for the March 2015 launch we wanted to see if the status had changed with the new parts. We asked for clarification and received this earlier today:

Hi Patrick,

SR-IOV is enabled on all SKUs we announced yesterday, and VT-d is also a feature of the CPUs.

We did ask for a clarification regarding whether there is a new D-1520 and D-1540 stepping that will enable SR-IOV on those platforms and we received the following:

At this point, there are no plans to enable SR-IOV in D-1540 and D-1520.

That is at least interesting considering the fact it was a feature touted in launch materials. It is possible that the SR-IOV in launch materials meant Xeon D processors that would eventually be released.


If you read through the 30+ page Intel Xeon D discussion thread on the STH forums or the SR-IOV with Xeon D testing thread you will see folks running into challenges with SR-IOV. At the end of the day, Facebook is one of the larger Xeon D customers an in its Yosemite Xeon D server it actually uses a Mellanox ConnectX-4 card for networking (see the lower left of this picture and here for the description.)

Facebook Yosemite Xeon D
Facebook Yosemite Xeon D

Performance on the onboard 10Gb ports for a lot of use is still good for many use cases. For example, in our Proxmox VE (KVM + LXC) and Ceph cluster we have in our Fremont, CA datacenter can push well over 1GB/s storage traffic over the NICs and to the VMs. In the initial cluster we used three Supermicro X10SDV-TLN4F based systems which have been working extremely well to the point additional nodes will be added this week.

We are happy to see that Intel has enabled SR-IOV on the new chips but wanted to get this information out so folks are at least aware of the earlier chip limitations.


  1. So I will return my 1540-Supermicro-Board and I will wait for the new ones.
    Any idea, when the’ll be released?


  2. Hate to update such an old thread, but possible this will help people still using this old hardware such as homelabbers.
    On my D-1540 X10SDV-8C-TLN4F I did update the bios and I CAN enable SR-IOV in the bios, but have yet to do any further testing yet…


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