Fusion

I'm running XP64 under VMware Fusion 1.1 on a MacPro with 16 GB of ram and would like to assign more than the 8 GB ram limit to the VM. What is the reason for the 8 GB limit and is there a work-around. (I've already tried editing the .vmx file memsize = "...." but get a message that 8192 is the max when I try to boot-up).

bump

I don't know the reason for the limit, but I suspect it has to do with overhead of keeping track of the virtual address space. It's not something you wan work around. However, I would also say any use case where you really need more than 8 GB RAM probably isn't a great use case for Fusion, and you should look into Boot Camp.

Etung,

Thanks for your reply. I think BootCamp would be a step backwards unless Apple has added 64-bit support for XP64 or Vista64. I'm running a 64-bit version of a finite element code (ANSYS-11.0) and a large FEA model that can almost run "in-core" with >9 GB of physical RAM. 10GB or more would avoid the the very high i/o involved with swapping the factorized matrix file back and forth. Maybe I'll have to check out parallels or crossover for this one, although I thought I read that the ESX VM servers could assign more than 8 GB of RAM so it doesn't appear to be impossible.

-Fred

I think BootCamp would be a step backwards unless Apple has added 64-bit support for XP64 or Vista64.

I believe Boot Camp supports 64-bit on recent Mac Pros.

Maybe I'll have to check out parallels

You should double check (e.g. on Parallels' forums), but I believe Parallels Desktop 3.0 is limited to 2 GB per virtual machine (wikipedia thinks so, as does searching their forums).

or crossover for this one

I'm not that familiar with Crossover's limitations, but I doubt they're better - they're geared more towards getting particular Windows apps working without Windows, but the tradeoff is compatibility; I doubt high performance computing like what you're trying to do is on their radar. I would start at http://www.codeweavers.com/support/

although I thought I read that the ESX VM servers could assign more than 8 GB of RAM so it doesn't appear to be impossible.

ESX is a totally different beast. It can do more than 8 GB RAM per virtual machine, but it's also a bare metal architecture as opposed to a hosted architecture.

As far as I can tell tell the latest version of BootCamp does indeed have 64-bit support. I won't say that definitively or assume that the support may not have issues still but I believe that you can run Windows XP x64 edition in BootCamp now. That being said, it would probably be more beneficial to run your application in hardware instead of the VM. Though I'll admit I did not fully understand what it is your running but I thought I would provide my 2 cents.

Aaron Davis

Just checked the Apple KB articles for Boot Camp which does indicate support for Vista64 with ver.2.1, but only when running with Leopard on recent MacPros & MacBookPros (2008 models). XP64 and prior MacPros appear to be excluded, although I'm not sure if "not supported" just means Apple's not interested in supporting XP64 and earlier configurations or there are real issues with them. I guess I'll need to experiment a little.

Also, being new to VMware I'm still a bit confused about the differences between a VM and Boot Camp installation of WindowsOS. Etang and Aaron in previous posts seem to indicate there is a significant difference, and that Windows in Boot Camp is running directly in hardware but not so in VM. Aren't Windows apps & MacOS apps both accessing the hardware, RAM, HDs, video cards, etc., via the same hardware controllers or is there some intermediate HAL that exists on the VM side that's not needed with Boot Camp? If so, what is the performance hit in VM?

I can't comment on the support for XPx64 on older systems but I would think if you have the most recent updates to leopard any intel mac would be able to run 64-bit operating systems with bootcamp. As far as running Windows in a vm no it is not using hardware directly like it would in boot camp. To an exstint it runs as if it were a physical machine but VMWare shares resources with the host OS at a somewhat low level operation. Depending on what your doing in the VM performance reductions are probably negligable. If your doing more work with 3d rendering or large mathematical calculations then you'd probably see better performance doing those sorts of things directly from a hardware instance. It really depends on the situation.

Aaron Davis