32-bit vs 64-bit guests

[jlmale0]

Using the wizard, I created a 64-bit guest environment and then, absentmindedly, installed a 32-bit OS. This works fine, as you would expect. However, aside from initial vnic choice* what are the differences between between a 64-bit and a 32-bit environment? Are these differences static, as with the nic choice, meaning you can only change them manually later? Or are they dynamic, taking effect only when the machine is powered on? For those not aware, once the machine exists, you can change the guest OS by following 'edit settings' -> 'options'; it's in the lower right of that window.

Now that I've asked about bittedness, does vmware make any optimizations or alternative choices for different operating systems?

• 64-bit guests start with the e1000 virtualized nic; 32-bit guests get the vlance nic

[jbogardus]

You can change the VM OS type setting after the VM is created. It will simply make some change to how performance is optimized for the VM when it is running. As for the NIC, after you have changed the OS type you can add a new nic to the VM and then remove the old one.

Some of the specifics are dependent on what VMware you are running. ESX? What version VC and ESX?

[drummonds]

Yes, that setting impacts a variety of features. Binary translation does not work on Intel 64-bit processors, as an example. By selecting a 64-bit OS when you are only using a 32-bit OS you have blocked your ability to select binary translation (or VMI, for that matter) on your guest OS. The addressing mode you select impacts monitor mode in complex ways. See .

Scott

More information on my communities blog and on Twitter:

http://communities.vmware.com/blogs/drummonds