Hardware Helps Software

So why are AMD and Intel eager to get involved in the fray? Because, as you may have heard Virtual PC-using Mac owners complain, handling virtualization in software comes at a price in degraded performance. Processor-level support reduces the overhead, handling some of the arbitration between OSes and adding hardware enhancements to facilitate virtualization -- giving the software layer a head start, so to speak, on building its phantom PCs.
"Since the time of the 386 and before, the CPU was built to run a single operating system," says Intel's Bohart. "If you go down and look at the nuts and bolts of the CPU, it's very much structured to facilitate a single OS that uses various levels of control to operate the platform. What [hardware] virtualization does is provide a mechanism so multiple operating systems can simultaneously run on the system and share the hardware."
Intel's virtualization optimization, formerly known by the codename "Vanderpool," has now been dubbed Intel Virtualization Technology or VT, and will debut in desktop processors later this year, with mobile and Xeon server variants due in 2006.
"What VT does is update [x86] architecture so there's an environment to more easily run multiple operating systems," Bohart explains. "With [greater] simplification, better performance, and manageability, VT is making it easier to deploy [or] easier to get to the point where we can talk about consumers having virtualization on their computers.
"A tremendous amount of the effort required to write [and manage] a virtualization software package ... can be designed out when you leverage VT," Bohart continues. "It's a situation where you could do it like in the past -- there are very successful software packages [today] -- but VT, by making some hardware fixes, offers an opportunity to greatly simplify that hardware layer. We see that as an opportunity to remove some barriers that maybe have prevented virtualization from being more widespread."
AMD is also rushing to woo developers and IT administrators to its implementation of the concept, called "Pacifica" and due in Opteron and Athlon 64 processors in the first half of 2006 (with a detailed specification to be released in April 2005).
Unlike the AMD64 extensions that added 64-bit capability to 32-bit x86 architecture -- and were more or less duplicated by Intel's EM64T -- Pacifica will not be a twin of Intel VT. Instead, AMD says, it will leverage special features inherent to the AMD64 platform, such as a memory controller built into the CPU instead of located on a separate chipset Northbridge.
"The way that we have designed our chipset enables us to provide a much more efficient piece of hardware in that one-to-many situation," says AMD's Auster. "It's our Direct Connect architecture, with an integrated memory controller, HyperTransport, and chipsets that communicate with one another and access memory directly."
Before either AMD or Intel comes close to shipping product, however, they've had to scramble for endorsements from virtualization software or hypervisor vendors. The Xen team has pledged to support both VT and Pacifica, while Intel unveiled a formal arrangement with VMware at its San Francisco forum and AMD says it has strategic alliances with both VMware and Microsoft.

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