AMD jockeys with Intel in software stakes

(continued from previous page)

to those commercial products: Xen, which is backed by a start-up called XenSource and supported by several computing heavyweights.

Programming jobs in Microsoft, VMware and Xen get a lot easier with virtualization support built directly into the processor. And in the case of Xen, help in building the support is coming directly from programmers at Intel and AMD.

"AMD will be supporting Xen by contributing a port of Xen to AMD's Pacifica technology," said AMD's Elsie Wahlig in a posting to a Xen mailing list. And Intel has been working on Vanderpool support.

Minor consequences from differences?
Lewis argued that whatever differences might exist in the AMD and Intel virtualization approaches, they will only affect those hypervisor parties.

Gartner analyst Martin Reynolds agreed, arguing that supporting AMD or Intel processors will require one-time work by the hypervisor makers. "Once you've done it, everything works," he said.

Eunice also said that the hypervisor makers are the most directly affected, but he said he believes others are involved--particularly when looking farther into the future, when virtual machine technology should let computer environments be packaged up and moved from one physical computer to another.

At that point, the decisions of AMD and Intel affect operating system makers, such as Red Hat and MontaVista Software; security software makers, such as Symantec and McAfee; and makers of midlevel software, such as BEA Systems and Oracle.

If AMD and Intel prove 95 percent compatible, "everything will be fine," Eunice said. But if there are differences in instructions, capabilities and mechanisms for handling failures, "then we have a problem with the forking of x86."

The x86 instruction set is largely the same between Intel and AMD. That means, for example, that Microsoft Windows and Adobe Photoshop will work on either.

A divergent instruction set could prove to be a problem. For example, while Intel was following AMD by adding 64-bit memory extensions to x86, Microsoft made it clear that it would support only one approach.

AMD's Wahlig hinted that Pacifica may vary from Vanderpool. "It's architecturally very similar to Vanderpool, though it does offer a different feature set and differing implementation, all designed to provide a richer environment for hypervisor-based virtualization," Wahlig said.

Lewis indicated that any variations aren't being added lightly. "Any features we put in that are not in Vanderpool are features we put in at the request of the virtualization software vendors," she said.

And differences need not be final. AMD and Intel went separate ways when adding new x86 instructions to speed multimedia operations, but eventually AMD built in support for Intel's standard as well as its own 3DNow.