Unfortunately, it's kind of a deal-breaker that each Mac OS X guest burns 100% CPU all the time. This is mentioned in the new user guide as something which will be fixed in a future release.
Ever since I bought my rarely-used Mac Mini, I've wished I could just drop OS X on my super-beefy Linux+Windows development machine. I hate having to have two keyboards, a monitor with two inputs, two mice or a switch, just to use OS X once in a while. And there's no way I'm giving up my model M for development.
You can use synergy to share keyboard / mouse between Linux, Windows and OSX. I use it between an Ubuntu desktop and a MacBook Pro. http://synergy2.sourceforge.net/
"Memory ballooning to dynamically in- or decrease the amount of RAM used by a VM (64-bit hosts only) (see the manual for more information)"
Awesome. I'm definitely not a VM expert, but I think that means I can fire up my VM, and if not much is running in it, it won't consume as much memory on the host. Is that correct?
The balloon driver, as others have pointed out, is used in an overcommit scenario as a way for the hypervisor to reclaim memory from a guest OS. There's a balloon driver loaded in to the guest which can communicate with the hypervisor. When the hypervisor needs more physical memory, it can ask a guest's balloon driver to inflate and start allocating physical memory pages. That will cause the guest to start reclaiming unused memory using it's native techniques; a Linux guest, for example, might destroy unused file buffer caches. The balloon driver can then release all the memory it's allocated and the guest won't bother reclaiming anything until it needs it.
I believe it's just memory overcommitment, so you can assign more memory than you actually have available on the host and it will dynamically handle it for you. Crazy stuff, though.
Memory ballooning is basically a mechanism for hypervisor to steal pages from the guest and yes, so it allows for over-commitment. Memory balloon driver is present inside the guest and hypervisor communicates how many pages it needs back to the driver. The driver allocates pages and sends it back to the hypervisor.
Depends on the country, as I understand it. Some countries like Germany allow it (prohibit Apple from certain terms in the license) , while other places (USA) it would be against license terms (I won't say illegal as that implies criminality; it would be a civil violation).
You're legally only allowed to run OS X Server virtualized on Apple hardware. VMware and Parallels have both implemented checks in their products to help Apple enforce this (although I believe they're somewhat trivial to work around).
IANAL, but as far as I understand, their EULA is sympathetic to running OS X on Apple hardware. So if you're running VirtualBox on OS X already, it might be alright with apple.
It is illegal to run OS X on a hardware not made by Apple, I guess it's fine to run it as a guest in a VM (the old Mac-on-Linux did that), although I can be wrong as well.
It is not illegal, to my knowledge no court has ruled on the matter and the only judgment (PYSTAR) that even remotely relates to OSX on no apple hardware and it had to do with copyright violations. Copyright protects distribution and public display of the media not the use of the private use of media. Companies have tried to blur this line by expanding what copyright encompass. If they want it to be illegal they need to provide a crypto key at the hardware layer that the software communicates with, as breaking cryptography does violate several laws.
Okay, thanks for the clarification, I wrote my original commentary without much caution, the user just not followed the EULA, that what I wanted to say, which to my knowledge is illegal in my country.
Thanks for the information, I'm Brazilian as well, I will study more about the legal situation, someone that worked in a large software industry here in Brazil (he is trustworthy), told me that it is illegal, I have to look further and not take for granted what people say to me.
I use VirtualBox as my dev environment every day and I know I'll be more productive when I can use both my monitors for development again. :)