VMware appliances

Andrew Back wrote: I believe the original VMWare used CPU Ring-3 to run the guest OS, and did a trap+emulate of the supervisor (ring 0) opcodes. However, OS/2 used ring 3 for itself, therefore it wouldn't work. It wasn't the I/O emulation that caused it to fail. Not sure whether modern VMWare still uses ring3, and whether OS/2 would work under VMWare when on Intel/AMD chips that support virtualization. VMWare Player is free. I've played with it once, it was ok, but too limited. VMWare Server is free, and runs much better than Player. I've used it for about 2 years for fun, and it worked very nicely for me. Though, sorry, haven't used it for OS/2. I didn't have to run it headless, but I did run VMWare Server 1.x over 2.x because the 2.x versions I've tried wanted the console to be launched inside a web browser, and I wanted it to be standalone. Everything worked just fine - network, USB, sound, video. No issues other than the file format was different, so when I wanted to move the vmware session to my Macbook which has VMWare Fusion, it had to convert the guest to its own format, which then couldn't be returned back to VMWare Server. Other than that, it was all peaches. ESXi is also free, but requires dedicated hardware and doesn't appear to allow sound playback across the network, though there may be ways around this depending on the guest OS. I've played with it a while and I do like it, but for me (personal use, not data center use), it's overkill. They are of course free as in beer, not as in speech. openvirtualbox is a bit more open source, but haven't played with it as VMWare Server and VMWare Fusion did the trick for my needs. Another thing is that virtualization is not emulation. :-) Except for the I/O layer and supervisor instructions, no emulation is involved. I'd be more worried about compatibility with your machine. Sometimes machines created on one chip will not work on another (if the guest OS sees a certain CPU and turns on features for that CPU and doesn't notice it was moved, you'll have issues.) The other problem I've mentioned previously. Different versions of VMWare use different file formats for their VMs. If you create a VM in VMWare Workstation, it probably won't work under VMWare Server 1.0, though it probably will work under VMWare Fusion. If you create a VM on a file system that supports 4GB+ files and you don't select the split into 2GB files, it may not work if your host's OS can't handle files larger than 2GB. So care must be taken to craft the appliances properly. Oh, that, and some guest OS's are commercial, therefore protected by copyright, therefore, it wouldn't be legal to distribute. No such issues with Linux VMs for example (assuming you stick to the free ones, and not something like RHEL.) I'd worry less about trust, though, there may exist exploits allowing something running in a guest to escape, as long as you don't allow the VM access to the network card, and don't give it access to executable files via the shared folders option, and don't give it access to devices such as USB drives, there's not too much it can do. :) YMMV, use care, etc.