Comments on: Linux Tip: How to Tell if Your Processor Supports VT http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/ Computer Help from your Friendly How-To Geek Sun, 08 Nov 2009 07:56:33 -0600 http://wordpress.org/?v=2.8.5 hourly 1 By: Ben Perove http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/comment-page-1/#comment-54402 Ben Perove Thu, 24 Jul 2008 07:03:09 +0000 http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/#comment-54402 Dell Bios (at least rev. A10) includes a Virtualization option where you can enable the extensions or turn them off (default). Without them, ESX server boots in 5 hours instead of 2 minutes. Dell Bios (at least rev. A10) includes a Virtualization option where you can enable the extensions or turn them off (default). Without them, ESX server boots in 5 hours instead of 2 minutes.

]]> By: Akshay Dayal http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/comment-page-1/#comment-23184 Akshay Dayal Tue, 25 Sep 2007 20:51:54 +0000 http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/#comment-23184 Is there any way to check if VT is enabled in the BIOS? Through a command line check? Is there any way to check if VT is enabled in the BIOS? Through a command line check?

]]> By: Robert Brockway http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/comment-page-1/#comment-21938 Robert Brockway Mon, 03 Sep 2007 04:30:38 +0000 http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/#comment-21938 Nothing in Qemu is non-open source anymore. In the past only kqemu kernel module was not OSS - the source code was available but the old licence was restrictive. This is all over with now. I understand the KVM developers are keen to merge their work with Qemu so I expect we'll see h/w virtualisation support in Qemu soon. Nothing in Qemu is non-open source anymore. In the past only kqemu kernel module was not OSS – the source code was available but the old licence was restrictive. This is all over with now. I understand the KVM developers are keen to merge their work with Qemu so I expect we’ll see h/w virtualisation support in Qemu soon.

]]> By: The Geek http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/comment-page-1/#comment-21735 The Geek Wed, 29 Aug 2007 05:24:40 +0000 http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/#comment-21735 Great comment... It's always nice when the readers add helpful information to the discussion, so thanks! Great comment…

It’s always nice when the readers add helpful information to the discussion, so thanks!

]]> By: jambarama http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/comment-page-1/#comment-21733 jambarama Wed, 29 Aug 2007 04:51:53 +0000 http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/#comment-21733 It looks to me that the VT extensions bit-size capability (32 or 64) is relevant to the physical processor, not to the guest. So enabling 32 bit extension on a 64 bit machine will definitely hurt performance (just like running a 32 bit OS on a 64 bit processor will hurt performance). It seems they are just a set of instructions used by VMs to reduce the performance hit from emulating x86 systems on x86 systems. The list of virtual solutions using these extensions where possible is a virtual who's who among VM software: vmware (esx/server/player), virtual box, xen, virtual iron, virtual pc, parallels, and others. More surprising to me is that kvm uses it and not qemu (maybe that is the closed source part of kvm). From Wikipedia: http://en.wikipedia.org/wiki/X86_virtualization Intel VT (IVT) Intel's virtualization extension for 32-bit and 64-bit x86 architecture is named IVT (short for Intel Virtualization Technology). The 32-bit or IA-32 IVT extensions are referred to as VT-x. Intel has also published specifications for IVT for the IA-64 (Itanium) processors which are referred to as VT-i. Intel VT was launched at the Intel Developer Forum Spring 2005. It is available on certain Pentium 4 6x1 and 6x2 models[2], Pentium D 9x0[1], Xeon 3xxx/5xxx/7xxx, Core Duo (excluding T2300E) and Core 2 Duo processors (excluding the T5200, T5250, T5300, T5450, T5470, T5500, E4x00, E2xx0). On some implementations, IVT support may be switched off in the Firmware. This can be determined by checking if the VMX flag is enabled by the Feature Control MSR. Documentation on the Intel website has stated that VT requires not only support from the processor, but also support from the chipset, BIOS, and perhaps software. Intel plans to add a technology named Virtualization for Directed I/O (VT-d) to VT. This provides a way of configuring interrupt delivery to individual virtual machines and an IOMMU for preventing a virtual machine from using DMA to break isolation. AMD virtualization (AMD-V) - SVM stands for "secure virtual machine) AMD's virtualization extensions to the 64-bit x86 architecture is named AMD Virtualization, abbreviated AMD-V. AMD-V is present in all K8 AMD (Athlon 64) processors from stepping "F" and all newer processors support AMD-V technology. This applies for all current Socket AM2 and Socket F processors. Not from Wikipedia: It looks to me that the VT extensions bit-size capability (32 or 64) is determined by the processor, not by the guest. So enabling 32 bit extension on a 64 bit machine will definitely hurt performance (just like running a 32 bit OS on a 64 bit processor will hurt performance). It seems they are just a set of instructions used by VMs to reduce the performance hit from emulating x86 systems on x86 systems. The list of virtual solutions using these extensions where possible is a virtual who's who among VM software: vmware (esx/server/player), virtual box, xen, virtual iron, virtual pc, parallels, and others. More surprising to me is that kvm uses it and not qemu (maybe that is the closed source part of kvm). It looks to me that the VT extensions bit-size capability (32 or 64) is relevant to the physical processor, not to the guest. So enabling 32 bit extension on a 64 bit machine will definitely hurt performance (just like running a 32 bit OS on a 64 bit processor will hurt performance). It seems they are just a set of instructions used by VMs to reduce the performance hit from emulating x86 systems on x86 systems.

The list of virtual solutions using these extensions where possible is a virtual who’s who among VM software: vmware (esx/server/player), virtual box, xen, virtual iron, virtual pc, parallels, and others. More surprising to me is that kvm uses it and not qemu (maybe that is the closed source part of kvm).

From Wikipedia: http://en.wikipedia.org/wiki/X86_virtualization
Intel VT (IVT)
Intel’s virtualization extension for 32-bit and 64-bit x86 architecture is named IVT (short for Intel Virtualization Technology). The 32-bit or IA-32 IVT extensions are referred to as VT-x. Intel has also published specifications for IVT for the IA-64 (Itanium) processors which are referred to as VT-i.

Intel VT was launched at the Intel Developer Forum Spring 2005. It is available on certain Pentium 4 6×1 and 6×2 models[2], Pentium D 9×0[1], Xeon 3xxx/5xxx/7xxx, Core Duo (excluding T2300E) and Core 2 Duo processors (excluding the T5200, T5250, T5300, T5450, T5470, T5500, E4×00, E2xx0). On some implementations, IVT support may be switched off in the Firmware. This can be determined by checking if the VMX flag is enabled by the Feature Control MSR.

Documentation on the Intel website has stated that VT requires not only support from the processor, but also support from the chipset, BIOS, and perhaps software. Intel plans to add a technology named Virtualization for Directed I/O (VT-d) to VT. This provides a way of configuring interrupt delivery to individual virtual machines and an IOMMU for preventing a virtual machine from using DMA to break isolation.

AMD virtualization (AMD-V) – SVM stands for “secure virtual machine)
AMD’s virtualization extensions to the 64-bit x86 architecture is named AMD Virtualization, abbreviated AMD-V. AMD-V is present in all K8 AMD (Athlon 64) processors from stepping “F” and all newer processors support AMD-V technology. This applies for all current Socket AM2 and Socket F processors.

Not from Wikipedia: It looks to me that the VT extensions bit-size capability (32 or 64) is determined by the processor, not by the guest. So enabling 32 bit extension on a 64 bit machine will definitely hurt performance (just like running a 32 bit OS on a 64 bit processor will hurt performance). It seems they are just a set of instructions used by VMs to reduce the performance hit from emulating x86 systems on x86 systems.

The list of virtual solutions using these extensions where possible is a virtual who’s who among VM software: vmware (esx/server/player), virtual box, xen, virtual iron, virtual pc, parallels, and others. More surprising to me is that kvm uses it and not qemu (maybe that is the closed source part of kvm).

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