[GoFaster2]

I thought I read somewhere that if you had two HD in a MacPro with dual graphics card and two monitors that you can install XP on one drive and os x on the other and run both at the same time. Somewhere someone did it and they also assign one processor to osx and one to xp? I have searched till my figures hurt but no luck. Is this possible?

[Big Mac]

You mean run two complete OSs at the same time on one motherboard? Utterly impossible. It simply cannot be done. The hardware ultimately has to be controlled by only one OS at a time. VMs like Fusion or Parallels offer the possibility to run a client OS on top of another, but that's very different from what you're describing.

[mduell]

Sure, it's called hypervirtualization. Windows, Linux, and many other operating systems support it, but unfortunately OS X does not.

Xen and VMware ESX are two popular options.

[Big Mac]

Interesting. I stand mostly corrected.

[mattyb]

Uh, think I agree with Big Mac, there is no way that two operatings systems could share the same hardware at the same time without any virtualization software involved. You cannot 'boot' a machine to run two OSes - unless someone has come out with a radical new way to do computing in the past few days.

[mduell]

Originally Posted by mattyb 

Uh, think I agree with Big Mac, there is no way that two operatings systems could share the same hardware at the same time without any virtualization software involved. You cannot 'boot' a machine to run two OSes - unless someone has come out with a radical new way to do computing in the past few days.

The hypervisor acts as a very basic operating system, and the guests run on top of it. No hardware is shared; some resources are assigned to each virtual machine.

[besson3c]

Originally Posted by mduell 

Sure, it's called hypervirtualization. Windows, Linux, and many other operating systems support it, but unfortunately OS X does not.

Xen and VMware ESX are two popular options.

KVM as well, I believe...

[mattyb]

Originally Posted by mduell 

The hypervisor acts as a very basic operating system, and the guests run on top of it. No hardware is shared; some resources are assigned to each virtual machine.

OK googled. Seems that a hypervisor sit between an OS and the hardware - why wouldn't this work on a Mac Pro? BIOS/Firmware issues ? Nothing to do with OS X if I understand the definitions of a hypervisor.

Not trying to be rude, just like learning about this stuff.

[P]

Originally Posted by mduell 

Sure, it's called hypervirtualization. Windows, Linux, and many other operating systems support it, but unfortunately OS X does not.

I'd prefer saying that no current virtualization product supports Mac OS X as a guest - Apple does permit virtualization in the Leopard Server EULA, and its patent filings show that they are working on it. Apparently virtualizing OS X is quite hard, as the mach kernel acts in a similar way already.

[besson3c]

mattyb: here's the thing... Xen requires kernel modifications to support para-virtualization for machine that don't include Intel's VT or AMD's XT chips. Additionally, Xen only runs on x86 hardware, but since all Apple's Intel hardware has included VT, this shouldn't be an issue. However, the Xen hypervisor itself also runs with support needed at the kernel level. This helps it perform better than hypervisors that don't (such as KVM), but adds to its overall complexity. So, for Xen to work under OS X, modifications to OS X itself would be necessary, this is is on Apple (since Apple will randomly release kernel updates that would overwrite Xen kernels)

The other approach gaining traction now is in a product called KVM, which is essentially a modified version of Qemu that includes full virtualization support by taking advantage of Intel VT/AMD XT. KVM does not require kernel modifications. However, it lacks some features that Xen has, and is a little slower performing most operations. It will let you devote your resources (such as RAM, processors, etc.) to VMs, but I'm not sure if it provides direct access to the machine's video card for stuff such as gaming. I believe that it provides a generic video subsystem of its own that is provided by the Qemu OS that drives the KVM hypervisor.

So, KVM should be able to run on OS X just fine, if not already. However, the "libvirt" interface written by Redhat that is quite handy for controlling and managing VMs running under either Xen, KVM, or Qemu hasn't been ported yet. Libvirt makes things like assigning resources and autostarting at boot easier, and it also includes a GUI (virt-manager). KVM and Qemu are purely command line tools.

It looks like development effort will be put into libvirt to bring it closer to what VMWare ESX will provide in terms of features.

VMWare ESX will do stuff like dynamically allocate resources to VMs as needed, allow you to take away resources from VMs at certain times of the day, and other computational optimizations to a VM environment. KVM just uses whatever resources you allocate to it.

Needless to say, OS X is very much missing out in the virtualization world. In addition to all of this, OS X itself won't run as a Guest OS, which is perhaps one thing that is holding it back within the community.

[besson3c]

Originally Posted by P 

I'd prefer saying that no current virtualization product supports Mac OS X as a guest - Apple does permit virtualization in the Leopard Server EULA, and its patent filings show that they are working on it. Apparently virtualizing OS X is quite hard, as the mach kernel acts in a similar way already.

VMWare Fusion is probably closest to VMWare Workstation under Windows/Linux, and Parallels is also similar to both in terms of its design and demographic.

In order to properly do what the OP wants, a more server-designed hypervisor would be needed to run under OS X - one that has separated its display from backend, one that can allocate resources on the fly in a more dynamic fashion, and likely one that includes command line (rather than GUI controls) and/or some sort of control API, as having command line controls will make it easier for other parts of the OS to interact with it and be aware of what it is doing (e.g. a non-vendor supplied OS X preference pane).

For those who care, VMWare and other virtual machine hypervisors are small Linux kernels in and of themselves. The next time you wonder what open source has ever done for you, VMWare (which was the first major virtualization product), likely Parallels, Xen, Qemu, etc. wouldn't exist without it

[mattyb]

cheers for the explanation besson3c - really eye opening. I've worked on z/VM and VMWare but always assumed (know where that gets you) that an operating system of some sort was needed before one could have the virtualization layer, which could 'host' other operating systems.

[besson3c]

Originally Posted by mattyb 

cheers for the explanation besson3c - really eye opening. I've worked on z/VM and VMWare but always assumed (know where that gets you) that an operating system of some sort was needed before one could have the virtualization layer, which could 'host' other operating systems.

Well, you're right... The hypervisor (virtualization layer) sits on top of an OS - it is not a fully bootable OS in and of itself (save the Xen kernels). The VMs that sit on top of this virtualization layer are given direct access to hardware, the hypervisor functioning as the mediator and traffic cop, providing the BIOS, etc.

Does this make sense?

[besson3c]

Actually, I should clarify...

You can run a virtualization layer without a full fledged host OS underneath it. You can do this using VMWare, and now with the new Redhat ovirt software that is in beta. Technically, VMWare and ovirt both run on a basic Linux OS, but this is a very lightweight, optimized, thin sort of shim that basically provides you with more of an appliance than a workstation OS + virtualization layer.

[mduell]

Originally Posted by P 

I'd prefer saying that no current virtualization product supports Mac OS X as a guest - Apple does permit virtualization in the Leopard Server EULA, and its patent filings show that they are working on it. Apparently virtualizing OS X is quite hard, as the mach kernel acts in a similar way already.

The OS X that most people have cannot be used as a VM guest per the EULA (which may or may not be enforceable in your jurisdiction). OS X Server allows virtualization, but it doesn't work with ESX and neither VMware nor Apple have decided to publicly state why.

[mattyb]

cheers again besson3c. your explanations are good - you should teach.

[P]

Originally Posted by besson3c 

For those who care, VMWare and other virtual machine hypervisors are small Linux kernels in and of themselves. The next time you wonder what open source has ever done for you, VMWare (which was the first major virtualization product), likely Parallels, Xen, Qemu, etc. wouldn't exist without it

Xen used to run on a Linux kernel, but recent versions no longer do. The concept of a hypervisor predates even UNIX by about a decade, and was always there in the back of everyone's mind when it comes to virtualization. Linux let developers implement it easily, but I'd say that it would have happened anyway.

The OS X that most people have cannot be used as a VM guest per the EULA (which may or may not be enforceable in your jurisdiction).

Same goes for most client versions of Vista (if not for XP).

OS X Server allows virtualization, but it doesn't work with ESX and neither VMware nor Apple have decided to publicly state why.

Moshe Bar, the founder of XenSource, has mentioned that he has looked in to it, but that the way Quartz communicates with the GPU made it tricky.

[besson3c]

Originally Posted by P 

Xen used to run on a Linux kernel, but recent versions no longer do. The concept of a hypervisor predates even UNIX by about a decade, and was always there in the back of everyone's mind when it comes to virtualization. Linux let developers implement it easily, but I'd say that it would have happened anyway.

Which version of Xen no longer runs on a Linux kernel? Are you sure about that?

[mduell]

Originally Posted by P 

Same goes for most client versions of Vista (if not for XP).

All non-third-world versions of XP allow running in a virtualized environment. Vista Business (which is the most like OS X, IMO), Enterprise, and Ultimate allow running in a virtualized environment.

[P]

Originally Posted by mduell 

All non-third-world versions of XP allow running in a virtualized environment. Vista Business (which is the most like OS X, IMO), Enterprise, and Ultimate allow running in a virtualized environment.

Home Basic and Home Premium still do not allow virtualization. There was talk about MS changing that, but they never did. Vista Business and Vista Ultimate do allow it, and I guess it's fair to say that they're more similar to OS X than the gimped Home versions, but Home Basic and Home Premium are hardly third-world versions. Vista Starter is the third-world version, but Home Basic is what you get from Dell if you don't ask for an upgrade.

[P]

Originally Posted by besson3c 

Which version of Xen no longer runs on a Linux kernel? Are you sure about that?

I'm sorry, I must have misremembered. VMware is the one moving away from Linux, and even that is not quite so clearcut: Apparently there still a bunch of Linux code (2.4 though, not 2.6) running even in the latest version.

[mduell]

Originally Posted by P 

Home Basic and Home Premium still do not allow virtualization. There was talk about MS changing that, but they never did. Vista Business and Vista Ultimate do allow it, and I guess it's fair to say that they're more similar to OS X than the gimped Home versions, but Home Basic and Home Premium are hardly third-world versions. Vista Starter is the third-world version, but Home Basic is what you get from Dell if you don't ask for an upgrade.

Which is exactly what I said.
"All non-third-world versions of XP allow running in a virtualized environment. Vista Business (which is the most like OS X, IMO), Enterprise, and Ultimate allow running in a virtualized environment." (emphasis added)