Virtual Machine Additions are such a nice enhancement when using Virtual PC, but apparently one that is not currently compatible with Server Core 2008. I first tried to install normally using VMAdditions.iso, but it comes up to a point where it tries to copy files, and fails, at that point during the MSI setup coming up with the message "Rolling back action:", with a progress bar that goes backwards. Soon the nonsensical screen "Setup Completed" is shown, with the additional information "Setup was interrupted before Virtual Machine Additions could be completely installed."
Looking at the setup log, it seemed like permissions may be an issue. But the setup process was running as an elevated Administrator on the machine. (Seems like you can't run anything as LUA in Server Core.)
Undeterred, from another full Server 2008 installation that had Virtual Machine Additions installed I copied the driver files from the Program Files folder. This is from version 13.803 of VMA. Then I tried this:
C:\>pnputil -i -a "c:\Program Files\Virtual Machine Additions\*.inf"
Microsoft PnP Utility
Processing inf : msvmmouf.inf
Successfully installed the driver on a device on the system.
Driver package added successfully.
Published name : oem0.inf
Processing inf : msvmscsi.inf
Successfully installed the driver on a device on the system.
Driver package added successfully.
Published name : oem2.inf
Processing inf : VirtualAudioDevice.inf
Failed to install the driver on any of the devices on the system : The required
section was not found in the INF.
Processing inf : vmadd_xp_drv.inf
Failed to install the driver on any of the devices on the system : No more data
is available.
Adding at least one driver package failed!
C:\>
For those that aren't familiar with the new pnputil command, it basically allows you to add and update drivers without having to use Device Manager. Earlier beta builds used to have a similar tool called drvload that had limited functionality.
So after running pnputil, things looked somewhat healthy, getting at least msvmmouf.inf and msvmscsi.inf onboard. I rebooted. But after coming up, the video display was in 16-color mode, and rendering was incredibly slow. Also no indication that any of the neat tricks available with Virtual Machine Additions had actually taken effect. It seemed like hard drive activity wasn't negatively affected, but the other niceties of Virtual Machine Additions hadn't taken effect. So to recover, I removed just the stuff that came from msvmmouf.inf like this:
C:\>pnputil -d oem0.inf
Microsoft PnP Utility
Driver package deleted successfully.
C:\>
After a reboot, things were back to where they were before, with no VMA. So that's everything I've tried. If anyone has any ideas of how to get VMA running under Server Core RC0, I'd be very interested to hear about it.