Does Windows 8.1 Hyper-V support VT-d?

[MorganX]

I can't find this information anywhere. Does anyone know if Win 8.1's Hyper-V supports VT-d? I know Svr 2k12 does.

[Raa]

Correct me if i'm wrong, but I thought you couldn't use Hyper-V without VT-d.

[Ambroos]

Correct me if i'm wrong, but I thought you couldn't use Hyper-V without VT-d.

VT-x. VT-d is something very specialized.

 

VT-d's only advantage is if you want to dedicate one specific PCI-Express slot/device to a VM. For example if you have an extra Gigabit Ethernet adapter in a PCI-Express-slot you could dedicate it to a VM, which would have almost complete native performance. Without VT-d there'd have to be address translation and stuff and it'd get slow.

 

If you don't want to do anything specific like that VT-d is completely unnecessary.

[MorganX]

VT-x. VT-d is something very specialized.

 

VT-d's only advantage is if you want to dedicate one specific PCI-Express slot/device to a VM. For example if you have an extra Gigabit Ethernet adapter in a PCI-Express-slot you could dedicate it to a VM, which would have almost complete native performance. Without VT-d there'd have to be address translation and stuff and it'd get slow.

 

If you don't want to do anything specific like that VT-d is completely unnecessary.

 

Or a Server with a dedicated NIC with high throughput or a sata controller for a VM with heavy I/O. Typically you want server for this but I have a 3770 and if 8.1 supports it, I'll go ahead and swap out my 3770k. For lab only, but I have it so might as well.

 

Edit: with many security appliances going VM you might want to dedicate NICs and I/O for logging, etc.

[Ambroos]

Well if you're serious about VM-ing you'll be running a bare metal hypervisor on dedicated VM hardware anyway, I hope. I doubt VT-d has much use otherwise.

[UseLess]

VT-d (Virtualization Technology for Directed I/O) has numerous uses, all centered (not surprisingly) around hardware IO. USB visualization and GPU pass-through are another two examples. This is a feature limited by the CPU in most cases.

[PGHammer]

Or a Server with a dedicated NIC with high throughput or a sata controller for a VM with heavy I/O. Typically you want server for this but I have a 3770 and if 8.1 supports it, I'll go ahead and swap out my 3770k. For lab only, but I have it so might as well.

 

Edit: with many security appliances going VM you might want to dedicate NICs and I/O for logging, etc.

Actually, VT-d (the D stands for Directed I/O) is even more niche/outlier than that - it allows you to dedicate to a guest I/O that the host cannot use or interfere with, especially of the host does not support the hardware in question.  (Typically, this feature is used for hardware-based security for VMs, such as dongles that high-end software can require - such as security appliances.)

 

Extra/dedicated network I/O is irrespective of VT-d with Hyper-V; by default, each network adapter available to Hyper-V is assigned its own virtual switch.  Because I have a wireless adapter (SMC USB wireless-G) that Windows Server 2003R2 and later supports, I can use it with any VM that is supported by Hyper-V, despite the Q6600 not supporting VT-d.  (Most Intel Core i-series CPUs and their progeny don't support VT-d, due to lack of support in their chipsets in addition to lack of support in the processors; Intel's Z-series chipsets (Z68/77/87) all lack support for VT-d, for example.)  Second-level address translation/extended processor table support (SLAT/EPT) is a requirement for Hyper-V support in Windows 8, but itself has nothing to do with VT-d; further, it's not a requirement for any version of Windows Server - and still isn't for Server 2012R2.  You DO want to dedicate I/O for VM responsiveness - however, you don't necessarily need VT-d to do so.

[MorganX]

Actually, VT-d (the D stands for Directed I/O) is even more niche/outlier than that - it allows you to dedicate to a guest I/O that the host cannot use or interfere with, especially of the host does not support the hardware in question.  (Typically, this feature is used for hardware-based security for VMs, such as dongles that high-end software can require - such as security appliances.)

 

Extra/dedicated network I/O is irrespective of VT-d with Hyper-V; by default, each network adapter available to Hyper-V is assigned its own virtual switch.  Because I have a wireless adapter (SMC USB wireless-G) that Windows Server 2003R2 and later supports, I can use it with any VM that is supported by Hyper-V, despite the Q6600 not supporting VT-d.  (Most Intel Core i-series CPUs and their progeny don't support VT-d, due to lack of support in their chipsets in addition to lack of support in the processors; Intel's Z-series chipsets (Z68/77/87) all lack support for VT-d, for example.)  Second-level address translation/extended processor table support (SLAT/EPT) is a requirement for Hyper-V support in Windows 8, but itself has nothing to do with VT-d; further, it's not a requirement for any version of Windows Server - and still isn't for Server 2012R2.  You DO want to dedicate I/O for VM responsiveness - however, you don't necessarily need VT-d to do so.

 

Thanks Hammer