Glorious wrote:That's undoubtedly a very important reason, but it's certainly not the only reason. The virtualization of videocard memory in userspace is generally just a good idea. Aero wouldn't be able to play well, if at all, with windowed 3d programs, if this aspect (and others) of WDDM didn't exist.
According to Microsofts own documentation it is done "primarily for security reasons" (direct quote). Interpret as you wish.
To me the why is not so important. There are now 768MB and even 1GB video cards now. With 2GB of user space and a 1GB video Card you are down to 1GB of user address space that didn't happen in XP.
There needs to be some kind of backward compatible mode in Vista for 32Bit programs, especially games that might need more than 1GB of user address space. It is hard to understand how something this fundamental slipped by Microsoft. We are talking about cutting a needed resource potentially in half, it should be obvious there is large potential for this to wreak havoc.