Virtual machines and OS X

Ryan Schmidt ryandesign at
Mon Nov 17 15:35:46 PST 2014

On Nov 17, 2014, at 3:33 PM, Michael Crawford wrote:

> VirtualBox' doc specifically warns that a guest might not run on a
> later CPU model than Apple tested it with during development.  I still
> find that surprising, as all the CPU vendors work really, really hard
> to enable upward compatibility - like the Xeon in my desktop box can
> still do 16-bit MS-DOS just fine.  I've never known Linux, Windows nor
> BSD to ever have a problem with later CPUs.
> However if it's a kernel panic, xnu - the OS X kernel - might have
> used a supervisor-mode machine instruction that works differently than
> it does on earlier model of CPU.  Because Apple makes both the

Well it certainly happens. Tiger, for example, which was never officially virtualizable, used to work in VMware, but stopped working when I upgraded to a new Mac, because of problems with the way Tiger boots up that were never a problem on any CPU Apple shipped with support for Tiger.

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