The current question of which Intel processors support the XP Mode feature in Microsoft's upcoming Windows 7 operating system shines a light on a relatively rare issue involving processor-OS compatibility.
Windows 7's XP Mode will let users run Windows XP-based applications in the Enterprise, Professional and Ultimate versions of the new operating system. The offering is another incentive for users to migrate from their older Windows operating systems to Windows 7, which is due out in early 2010, although many industry observers expect it to launch in 2009 before the holiday season.
John Spooner, an analyst with Technology Business Research, said XP Mode is the perfect example of how virtualization technology can be used in desktops and laptops.
"That is what's great about desktop virtualization," Spooner said. "In this case, it lets you run your older [XP] applications on Windows 7."
The issue that has come up in recent days is that not all Intel chips-or those from Advanced Micro Devices, for that matter-offer the hardware-based virtualization technology that is needed to take advantage of XP Mode.
This will particularly hit consumers, who are more likely than businesses to buy laptops and desktops powered by lower-end processors, which tend not to have the chip makers' virtualization technology. Not putting in the virtualization technology enables chip makers to keep down the cost of those low-end processors, Spooner said.
Almost all AMD chips except those in the low-end Sempron line offer the AMD-V virtualization technology, said Margaret Lewis, director of commercial solutions at AMD.
As for Intel, most of its enterprise-level processors offer Intel VT virtualization capabilities, said spokesperson George Alfs. Intel introduced the technology in 2005 and has shipped more than 100 million chips with the feature since then.
In a statement, Intel said, "Windows XP Mode is targeted for business customers. It is available on the mid- to higher-end versions of Windows 7 and is supported in hardware by many Intel processors. Intel vPro technology PCs are required to have an Intel VT-capable CPU and Intel VT-capable BIOS. They are the best platforms for testing and deploying Microsoft Windows Virtual PC and Windows XP Mode."
The AMD and Intel virtualization technologies are BIOS settings, and AMD's Lewis said many system makers ship their machines with the feature turned off.
While the issue of whether a chip has the virtualization technology to support XP Mode is primarily a consumer problem, and can be determined quickly enough, determining whether the virtualization capability is turned on or off could become a headache for some businesses, Spooner said.
"For a lot of systems, [making that determination] is going to require a desktop visit [by an IT staff member], which can be expensive," he said. "But I'm not sure if there is a remote way to figure that out."
Lewis said the issue highlights that area where "hardware and software really touch," and where chip makers work closely with Microsoft to ensure compatibility.
Both she and Alfs said compatibility with Windows is rarely an issue. AMD and Intel engineers work closely on an ongoing basis with their Microsoft counterparts not only as the operating system is being developed, but also as the chip makers lay out plans for future processors and architectures, they said.
Alfs said Microsoft builds its Windows OS on the x86 architecture, and the long beta testing cycle the software maker undertakes ensures close compatibility with Intel hardware designs. In addition, Intel gives Microsoft a long view of its product development plans. For example, Intel engineers already are sharing information with Microsoft about "Sandy Bridge," the chip architecture that will replace "Nehalem" sometime in 2010 and will offer such features as on-chip graphics technology and the AVX instruction set.
"These are chips and platforms that are not even on the market yet," Alfs said.
Lewis said in most cases, the hardware is given to software makers, who then ensure that their offerings are compatible. For example, Windows 7 will take advantage of AMD's RVI (Rapid Virtualization Indexing), which enables better management when hypervisors, a guest OS and applications are involved, she said.
"The hardware is presented to the software [makers], and then they put their magic into it," Lewis said.