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I have a Z68 motherboard that is capable to run an Ivy Bridge CPU which features VT-d. Currently, I do not have such a CPU, but I plan to upgrade it so I am able to pass PCI devices (Ethernet and graphics card) to a QEMU machine for testing.

However, I see much contradictory information on the support of VT-d for this Z68 motherboard.

Assume that a CPU supports VT-d. Is motherboard support for VT-d determined by software (BIOS) or hardware (some additional chips or hardware logic)?

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It would probably help if you told us what motherboard you have... However, in general, without an option in the BIOS to explicitly enable it, it may just stay disabled for security reasons. – Breakthrough Jun 18 '13 at 20:20
I tried to keep this question more generic, but since you insisted, the motherboard is GA-Z68X-UD3H-B3 rev1.0. There is no official option, but the provided images in this forum thread do add an Enable VT-d option. (though I cannot confirm whether it works or not since I do not have a VT-d capable CPU yet.) – Lekensteyn Jun 18 '13 at 20:25
Yes, but have a look at the last reply in that thread from a Gigabyte employee. Indeed, it appears as though the Z86 Express does not have VT-d support... But you are correct in your assumption, both the CPU and motherboard/chipset both need to support VT-d. – Breakthrough Jun 18 '13 at 20:30
That user does not look like a GA employee. Isn't Z86 Express referred to from Z68X? My question still stands, is VT-d support dependent on the hardware (motherboard!) or firmware (BIOS)? – Lekensteyn Jun 18 '13 at 20:56
Ah sorry my mistake. However, still note that the Intel site says the Z68 Express chipset does not have VT-d support... (this makes Breakthrough sad because he too has a Z68 board). – Breakthrough Jun 18 '13 at 20:57
up vote 0 down vote accepted

I am now running an i7 3770 with a GA-Z68X-UD3H-B3 (rev 1.3) motherboard on BIOS U1l. VT-d seems to work, I can successfully pass PCI devices to a QEMU instance.

Modern Intel CPUs have the North bridge integrated in the CPU package. Thus, at least for the Sandy Bridge and Ivy Bridge CPUs, the VT-d functionality is provided by the CPU itself (the hardware part). The BIOS must still be configured to provide the necessary information toe the host (software). There does not seem to be an additional hardware requirement if I am not mistaken.

(source: pure guess-work and anecdotal evidence from myself)

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