At this point, you can see that there is a lot of effort for putting all of this to work. In fact, this architecture is only possible because hardware and software companies worked together in the past. The main goal of both type of companies was to enable virtualization of operating systems without changing them.
Intel and AMD created, each one with its own implementation, a processor feature called virtualization assistance so that the Hypervisor could run on Ring 0, as explained before. But this is just the first requirement. There are other requirement as well, which are as follows:
Virtualization assistance (also known as Hardware-assisted virtualization): This feature was created to remove the necessity of changing the OS for virtualizing it.
On Intel processors, it is known as Intel VT-x. All recent processor families support this feature, including Core i3, Core i5, and Core i7. The complete list of processors and features can be found at http://ark.intel.com/Products/VirtualizationTechnology. You can also use this tool to check if your processor meets this requirement which can be downloaded at: https://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=1881&DwnldID=7838.
On AMD Processors, this technology is known as AMD-V. Like Intel, all recent processor families support this feature. AMD provides a tool to check processor compatibility that can be downloaded at http://www.amd.com/en-us/innovations/software-technologies/server-solution/virtualization.
Data Execution Prevention (DEP): This is a security feature that marks memory pages as either executable or nonexecutable. For Hyper-V to run, this option must be enabled on the System BIOS. For an Intel-based processor, this feature is called Execute Disable bit (Intel XD bit) and No Execute Bit (AMD NX bit). This configuration will vary from one System BIOS to another. Check with your hardware vendor how to enable it on System BIOS.
x64 (64-bit) based processor: This processor feature uses a 64-bit memory address. Although you may find that all new processors are x64, you might want to check if this is true before starting your implementation. The compatibility checkers above, from Intel and AMD, will show you if your processor is x64.
Second Level Address Translation (SLAT): As discussed before, SLAT is not a requirement for Hyper-V to work. This feature provides much more performance on the VMs as it removes the need for translating physical and virtual pages of memory. It is highly recommended to have the SLAT feature on the processor ait provides more performance on high performance systems. As also discussed before, SLAT is a requirement if you want to use Hyper-V on Windows 8 or 8.1. To check if your processor has the SLAT feature, use the Sysinternals tool—Coreinfo— that can be downloaded at http://technet.microsoft.com/en-us/sysinternals/cc835722.aspx.
There are some specific processor features that are not used exclusively for virtualization. But when the VM is initiated, it will use these specific features from the processor. If the VM is initiated and these features are allocated on the guest OS, you can't simply remove them. This is a problem if you are going to Live Migrate this VM from a host to another host; if these specific features are not available, you won't be able to perform the operation. Live Migration and Share Nothing Live Migration will be covered in later chapters. At this moment, you have to understand that Live Migration moves a powered-on VM from one host to another. If you try to Live Migrate a VM between hosts with different processor types, you may be presented with an error.
Live Migration is only permitted between the same processor vendor: Intel-Intel or AMD-AMD. Intel-AMD Live Migration is not allowed under any circumstance. If the processor is the same on both hosts, Live Migration and Share Nothing Live Migration will work without problems.
But even within the same vendor, there can be different processor families. In this case, you can remove these specific features from the Virtual Processor presented to the VM. To do that, open Hyper-V Manager | Settings... | Processor | Processor Compatibility. Mark the Migrate to a physical computer with a different processor version option. This option is only available if the VM is powered off.
Keep in mind that enabling this option will remove processor-specific features for the VM. If you are going to run an application that requires these features, they will not be available and the application may not run.
Now that you have checked all the requirements, you can start planning your server for virtualization with Hyper-V. This is true from the perspective that you understand how Hyper-V works and what are the requirements for it to work. But there is another important subject that you should pay attention to when planning your server: memory.