I have been running VirtualBox 3.x on my personal Solaris Desktop as well as my work laptop. About 2-3 weeks ago, I upgraded to VirtualBox 4.x on my work laptop. Upgrade was simple and easy. I have seen considerable improvement of the way the VM Screens are handled in 4.x. The fullscreen mode is really fullscreen now and the Host Key functionality improved tremendously.
All these two weeks, I was thinking in the back of my mind about the Solaris version of the same upgrade, for my personal desktop. Didn’t spend much time on that till this morning though. This morning, downloaded VirtualBox 4.0.4 for Solaris and installed it. The installation was fairly straight forward: Uninstall it from the global zone and reinstall the new package. One notable fact though: The older version, during the uninstallation process, never checked if the application is running in the first place. It simply uninstalled, while my VirtualBox is running and a couple of VMs are in suspended state. During the install of the new version, it checked for the presence of running processes and aborted installation with the right error message. I had to stop the application and then reattempt the installation.
Having OpenSolaris 2009-06 (build 111b) installed on my system, I got a warning during installation about USB support for guests (which requires build 124 or later I guess). Other than that, the upgrade on OpenSolaris went on simply fine and I am back with all my VMs. I also installed a new instance of Ubuntu server on VirtualBox, just to test out the functionality. It is working fine (able to identify all the .vdis, grab all the previously uploaded disk images, etc.