[vfio-users] How to choose a compatible motherboard?

[Lucas Neves]

Hi Corey,

I'm afraid that the E5-1620 V3 doesn't have an integrated GPU. I'm not sure
though, since Intel simply omitted the "graphics specification" section
from its page:
http://ark.intel.com/products/82763/Intel-Xeon-Processor-E5-1620-v3-10M-Cache-3_50-GHz
.
So you would need a separate video card for your host system, if you want
to use Linux as a desktop. That's why I chose the i5-4690k over a Xeon.

For the record: my Radeon r9-285 by ASUS works with OVMF, but if I turn the
guest off, I need to reboot the host. Guest soft-reboots are fine.

I think that my ASUS Z87-PRO would yeald a proper IOMMU configuration if I
had only one video card. But I also have an Nvidia GTX-660, that I use for
the Linux host, and both the Nvidia and the ATI cards are put in the same
IOMMU group. So I need Alex Williamson's patch to enable overrides for
missing ACS capabilities. This patch creates DMAR problems that affect my
Intel i915 HDMI audio, used by my wife's seat -- yes, I'm running KVM on
top of a multiseat system. These DMAR issues are fixed by disabling IOMMU
for the integrated graphics, booting with
CONFIG_CMDLINE_LINUX=intel_iommu=on,igfx_off. Phew!

Good luck!
Lucas


On Thu, Oct 22, 2015 at 10:42 AM Corey Larson <corey at eatrunco.de> wrote:

> Thanks for all the help, everyone! I really appreciate it.
>
> So, to summarize and make sure I have condensed all this info properly,
> the consensus seems to be that:
>
>   1. Current Skylake CPUs are a bad choice for vfio builds (because of a
>   lack of ACS).
>   2. Xeon E5 CPUs are good. E3 and Core iX CPUs are bad for vfio
>   (because of a lack of ACS).
>   3. Look for motherboards that explicitly list VT-d as a feature. ASUS
>   boards seem to be wonky. People seem to have good success with ASRock
>   boards.
>   4. Configurations that rely on the ACS override patch may act weird,
>   and are less likely to be supported. Which makes sense given the
>   nature of the patch.
>
> As I was researching a build to leverage vfio, I did read AW's blog
> posts, but had thought "Xeon? I'm not made of money!" After seeing it
> pushed more on this list, I did more research and found that some of the
> "entry-level" Xeons (specifically the E5-1620 V3) are very much within
> the realm of regular people.
>
> Additionally, from those links to the HW lists, it seems that the an
> ASRock (in my case, a X99 Extreme4 since its cheaper than the 6, thanks
> for the pointer Nick) paired with a Xeon E5-1620 V3 is a practical and
> cost effective solution.
>
> Thanks again!
>
> On Wed, Oct 21, 2015, at 11:26 AM, Corey Larson wrote:
> > I am in a position where I can do a new build with this technology in
> > mind. How do I go about picking a motherboard that will have the best
> > compatibility to do vfio?
> >
> > Currently, my plan is to use this board:
> > https://www.asus.com/us/Motherboards/H170-PRO-GAMING/specifications/. I
> > plan to add an additional GPU (NVidia GTX 960) for the guest, and use
> > the integrated Intel graphics to drive Linux. I also plan to make use of
> > OVMF to avoid the Intel VGA arbitration patch.
> >
> > I appreciate any information you can share with me to help guide me!
> > --
> > Corey Larson
> > corey at eatrunco.de
> >
> > _______________________________________________
> > vfio-users mailing list
> > vfio-users at redhat.com
> > https://www.redhat.com/mailman/listinfo/vfio-users
>
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