A Concrete Reason Macs Beat PCs: Intel VT

Posted on 07. Aug, 2009 by Stephen in Apple, Computer history, Terabyte home, Virtual Storage

There is a lot of FUD flowing between Apple Macintosh true believers and the rest of the PC world. This is especially true now that Macs use Intel CPUs, NVIDIA chipsets and graphics, and so much more commodity PC parts. Lots have argued that a Mac is just an expensive PC with a flashy case and slick operating system. Mac fans have to admit that there is a lot of commonality (Macs and PCs can even run each others’ operating systems with varying degrees of success), but contend that Apple uses superior components, justifying the “Apple tax”.

This last point has always been debatable as well. Apple tends to select higher-end x86 parts for their Macs and has led the way with innovative chassis, screen, and trackpad technology. But PC makers have quickly followed, offering part-for-part Apple clones at 80% of the cost. This week, however, I stumbled onto a concrete difference between Mac and PC hardware that has real-world impact: Across the board, Apple uses exclusive Intel CPUs with enhanced capabilities to support virtualization of 64-bit operating systems, including Windows 7’s special XP compatibility mode.

Virtualization-Ready

Virtualization hypervisors have become very widespread and popular, especially in the Apple world. Mac users regularly list Parallels Desktop and VMware Fusion among their favorite applications, since they open up the wide world of Windows applications running in a virtual machine. Although most daily tasks can be performed with native OS X applications, some apps just aren’t available.

Personally, I use Fusion on OS X with Windows Vista to occasionally run Microsoft’s Visio and Outlook, both of which aren’t available as native applications. I also use a 2009 Mac Mini as a server and virtual computer lab, mainly relying on Sun’s lightweight and free VirtualBox hypervisor. Although it isn’t impressive as the physical lab Dennis Martin described to me last week, I am able to run a variety of servers (Linux, Windows, and OS X) and other virtual gear (Windows Storage Server and FreeNAS) to simulate enterprise IT environments.

Windows users have less need to run virtualization applications: When your operating system commands over 90% of the market, a whole world of applications is at your fingertips! But enthusiasts and corporate IT types love virtualization, and VMware Server and Microsoft Hyper-V are commonly found on their Windows machines.

64-Bit Road Block

These popular virtualization packages support a wide range of modern hardware, but not everything works perfectly. Hypervisors had trouble with many tasks, particularly running 64-bit operating systems, until Intel and AMD introduced special hardware-assisted virtualization capabilities in their CPUs. The latest hypervisors and CPUs can now even virtualize 64-bit operating systems on top of 32-bit hosts!

But not all CPUs include this technology. Intel has a long history of artificially segmenting their product line by disabling certain features in low-end parts. For their Core 2 Duo “Merom” and “Penryn” lines, Intel decided that their VT virtualization technology would be the differentiator. Therefore, a lack of VT support is one of the main differences between low-end and high-end Intel Core 2 Duo CPUs.

Many of the latest portable and compact desktop systems use Intel’s Penryn-3M line, including Apple’s MacBook, MacBook Pro, and Mac Mini systems. See the issue here? Intel’s lower-end 2.0 GHz and 2.133 GHz CPUs (P7350 and P7450, respectively) don’t support VT, which means that systems using them don’t have the latest VT hardware virtualization capability and thus can’t run 64-bit virtual machines!

This is an issue for users of popular Sony Vaio, Dell Inspiron, and HP Pavilion PCs, and is likely to become much more important soon. See, Windows 7 includes a special XP compatibility mode, which is really just a virtual machine running XP under 7. But XP mode will not work without Intel VT or AMD-V. This means that XP mode in Windows 7 won’t work on the very mass-market machines that would benefit most from it!

Apple’s Different

This sounds terrible: The latest machines won’t run increasingly-popular virtualization software. But there is a very good reason that buyers of the latest Apple machines aren’t up in arms. It seems that Apple made a deal with Intel to get a special version of the Penryn-3M Core 2 Duo CPUs that do support Intel VT!

Apple’s latest Mac Mini, MacBook, and MacBook Pro all sport P7350 and P7450 CPUs, just like competing Dell, Sony, and HP machines. But the Apple CPUs have VT and the PCs lack it. The VT support is gone, and cannot be enabled in the PC BIOS.

So even a PC and Mac sporting the exact same CPU part numbers aren’t equal: Every recent Mac will run 64-bit Windows and XP mode in Windows 7 and many PCs won’t. And I can run anything I want on my Mac Mini virtual lab!

Update - Let me be very, very clear on the facts here:

Most hypervisors now require Intel VT or AMD-V in order to virtualize 64-bit operating systems

Microsoft requires this technology to use XP mode in Windows 7

All current Apple Macs (including those that use P7350 and P7450 CPUs) have Intel VT support in their CPUs regardless of what Intel says on the model spec sheets

Many PCs use high-end Intel and AMD CPUs that support VT or AMD-V, though some have this turned off in the BIOS

No PC with an Intel P7350 or P7450 CPU has Intel VT support at all. It cannot be enabled in the BIOS because it does not exist.

I am not an Apple fanboy. I am a virtualization fanboy who is glad I bought a Mac Mini instead of a Dell Studio, HP TouchSmart, or Sony Vaio.

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Tags: 64-bit, AMD, AMD-V, Apple, Apple tax, Core 2 Duo, Hyper-V, Intel, Intel VT, Mac Mini, MacBook, MacBook Pro, Microsoft, NVIDIA, Outlook, Penryn, VirtualBox, virtualization, Visio, VMware, VMware Fusion, Windows 7, Windows Storage Server, Windows Vista, XP mode

David Hesse

thanks for this article. I wish I would have found this one BEFORE i bought my new Dell Studio. I am totally disappointed by the fact that I have a 64 bit capable Intel Core Duo Processor, that does not support Hardware Virtualization and it was nowhere stated in the specs on the Dell Website.
I will have to give that thing to my girlfriend and by a new machine.
Thanks for the tip with the Mac Mini's. That is actually a great idea. Let me see what they cost nowadays......

Ben Dover

Macs are the same as PC's because they run the same hardware. Cheaper CPUs have no virtualization support so Macs just use the ones that do have that support.

Wes

Are you quite sure about this? My two year old PC supports VT. Most PCs allow you to cut this support on and off through a setting in the BIOS.

sfoskett

Yes, PC BIOS often lets you turn VT on or off. But you can't enable it if it doesn't exist, and there are a large number of Intel CPUs (including the P7350 and P7450) that simply do not have VT support at all. These are very popular chips and are used in lots of PCs.

The amazing thing is that Intel made special P7350 and P7450 chips just for Apple which do have VT support. This is different hardware with the same name!

Louis G. Wheeler

I suspect, Wes, that it has to do with the price and quality of the PC. Some PC models will be VT capable just like some are Areo capable. That is often because they are Pro machines, rather than consumer models.

The problem is that this capability may not be readily apparent. Microsoft / Intel might be getting another black eye when System Seven is released. Many people will be irritated because their recently purchased computer is not VT capable. Hence, it cannot run windows XP in virtual mode.

Viswakarma

Omnigraffle Pro and ConceptDraw Pro are two very powerful alternatives for Visio on the Macintosh.

Louis G Wheeler

Thank you, Steven, for posting this. This was quite interesting.

Much of the article had to do with Wintel's shortcomings, but the revelation that Apple has included hardware VT in all of its product lines needs to be thought about.

This is a case where paying more gives great benefits. It explains why Bootcamp, VMware and Parallels can provide the Windows OS in its own virtual space and partition.

Moreover, we need to think about what will be the consequences of adding Snow Leopard's 64 bit operating system to Intel 's 64 bit virtual technology hardware -- VT-i. From what I've read, the real strength and flexibility doesn't appear until you are using a 64 bit computer.

Intel VT-i was really designed to work with Intel's V-Pro software to overcome the shortcoming of the Windows OS. It sand boxes each OS, Application and memory in its own virtual space. Both of the above are aimed at the Enterprise market; they give a central agency an ability to control what privileges and resources a user, an operating system, an application or a thread gets.

I suspect that Apple will be providing much of the capability of V-Pro inside Snow Leopard, but I do not think that this is its major intent.

Leaked pictures of Snow Leopard show that most processes are sand boxed. I saw one screen with a misbehaving plugin to Safari which was taking too many computer cycles. It was easy to delete that process and start it anew. Whereas in Leopard 10.5, you had no idea what was hanging up Safari.

We don't know what opportunities that Snow Leopard will offer us, but it seems likely that the Mac OS and the Windows OS will operate in their own virtual space. It will look to the user as though the windows for each OS co-exists next to each other when they are completely isolated. The implications for security are enormous if every OS, application and plug in is sand boxed.

Apple said recently that Snow Leopard would be getting much improved security, but it didn't quite say how. The Wintel pundits immediately jumped on this with their imputation of "Security by Obscurity." Partly this is true, but the reason is not because of Apple's small market share. Part of Security by Obscurity is to hide from hackers where essential operating files are in a 64 Terabyte address space. They cant steal or misuse what they can't find.

What the combination of Snow Leopard and Intel VT-i will give is "Security by Isolation." You will be able to set up a secure process with your bank or vendors which will be isolated from the rest of the computer in a virtual process and partition. Even if a vulnerability gives a hacker root access for the main part of your computer which is not secured, it will not even see the isolated sand boxed parts in their own virtual space.

Name

"This means that XP mode in Windows 7 won’t work on the very mass-market machines that would benefit most from it!" Ah Ha! you have discovered the method to Microsoft's madness. If ya want to run XP on your Windows 7 machine, you most likely will have to buy a new computer. That makes Microsoft's hardware partners very happy.

Stephen Foskett, Pack Rat