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Re: [Xen-users] ASRock B85M Pro4 micro-ATX Motherboard Supports VT-d!!!

I have an interesing update.

Yesterday Supermicro replied me to an E-Mail I send a week ago

My E-Mail:

Subject: Intel VT-d support on LGA 1150 Motherboards

I have been interesed in purchasing a LGA 1150 Motherboard for a Haswell build, possibily with a Xeon E3-1245 V3. One of the requisites is that it supports VT-d, so I can use the IOMMU feature to do VGA passthrough with the Xen Hypervisor. There are many consumer Desktops Motherboards from other brands that usually does NOT support VT-d due to the lack of a proper ACPI DMAR table in the BIOS, rendering the feature useless even through there seems to be Hardware support. This is the reason why I started to pay attention to Server oriented Motherboards like yours.

I started to look Supermicro X10SAT Motherboard, that claims in the manual VT-d support. However, one of the reasons why I don't find Server Motherboards convincing is that while I believe they would do the job properly, I will miss all the BIOS arsenal of options to run it out-of-spec (Overclocking/underclocking, overvolting/undervolting the Processor, RAM Timmings, etc), that are very rare to see on a Server Motherboard. There is also another Motherboard similar to the X10SAT, the C7Z87-OCE, which seems to have all those options that I want to have, and also claims VT-d support in the manual, so it seems like a better choice.

However, Intel Ark site says that the Z87 Chipset does not support VT-d, while C226 Chipset does:


Can Supermicro confirm if VT-d works on the C7Z87-OCE and if that Chipset info is wrong on Intel part?

Besides, accoding to photos, the X10SAT and C7Z87-OCE seems to be based on the same PCB, so they should be very similar. Are there any more feature that doesn't prominently appear on the specifications page that I'm missing by going to one choice against the other, like the BIOS options

Supermicro response:

Since Z87 chipset does not support VT-d, onboard LAN will not support it either because it is connected to PCH PCIe port. One workaround is to use a VT-d enabled PCIe device and plug it into CPU based PCIe-port on board. Along with a VT-d enabled CPU the above workaround should work per Intel. As for X10SAT, although it shares the same PCB as C7Z87-OCE, will not have overclocking options enabled in the BIOS since that was not what it is designed for.


This is extremely interesing. Basically, what I understand is that they say that you DO need Chipset support for VT-d, but only for devices connected to the Chipset PCIe lanes, while Processor PCIe lanes should work independently. What I didn't understand is if the workaround is to make the Chipset devices work with VT-d using the Processor support instead of Chipset.

I still insist that it will be very useful if someone gets a Intel guy that can explain in-depth this.

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