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Hardware Requirements For 64-Bit Guest Operating Systems

Thursday, 11 May 2006 by Michel Roth

VMware's virtual machine monitor has traditionally used segmentation to provide isolation between the guest operating system and the virtual machine monitor. This is necessary because the guest operating system and virtual machine monitor share the linear address space.

AMD
Segmentation support is missing from the initial AMD64 processors (that is, revision C and earlier) while running in long mode. As a result, AMD64 processors prior to revision D do not have an efficient mechanism for isolating the virtual machine monitor from 64-bit guest operating systems.

A limited form of segmentation was reintroduced in long mode, in revision D AMD64 processors. As a result, AMD64 processors must be revision D or later to run 64-bit guest operating systems.

Note: Because AMD Opteron and Turion processors do not ship in revision D, AMD Opteron and Turion 64 processors must be revision E or later to run 64-bit guest operating systems.

Intel
Intel EM64T CPUs do not have segmentation support in long mode. If the Intel EM64T CPU is VT-capable, it comes with hardware virtualization support (Intel's Vanderpool Technology). This hardware virtualization support allows Workstation and VMware Server to work around the lack of segmentation, making it possible to run 64-bit guest operating systems on Intel EM64T VT-capable CPUs.

32-Bit CPUs
Please note that Workstation and VMware Server require a 64-bit CPU to run a 64-bit guest operating system. While it is theoretically possible to emulate a 64-bit instruction set on 32-bit hardware, doing so most likely results in unacceptable performance degradation.

VMware distributes a free utility that can be used to determine whether or not your CPU is suitable for running 64-bit guest operating systems. You can download this utility from the VMware Web site at www.vmware.com/download/ws/#utilities. VMware Server includes this utility in its product distribution, so you don't need to download an additional tool.

Workstation 5.5 and VMware Server 1.0 support virtual machines with 64-bit guest operating systems only on host machines that have one of the supported 64-bit processors:

AMD Athlon 64, revision D or later
AMD Opteron, revision E or later
AMD Turion 64, revision E or later
AMD Sempron, 64-bit-capable revision D or later (experimental support)
Intel EM64T VT-capable processors (experimental support)

Read more here.