John R Pierce wrote: > On 02/11/11 8:39 AM, m.roth at 5-cent.us wrote: >> They have*everything* to do. Look, I*said* this is OT, but since you >> insist, the overwhelmingly*bad* design decision was to put the GUI into >> ring 0, instead of the way Windows 3, and X on*Nix, and *everybody* >> else did, resulting in a GUI error bringing down the*entire* system. > > the "GUI" is a fairly nebulous term. The graphics display driver > is indeed at ring zero for performance (in fact in early versions of NT, > it ran in ring 1 or 2, but the performance hit of the ring transitions > to access IO ports on early graphics cards was overwhelming so in NT4 it > was moved to ring0). However, the GDI, User (window manager), desktop, > and about everything else are in ring3 user space. I'll assume that you've actually worked with the code; I haven't. However, I also trust it about as far as I can through a sumo wrestler, since I *know* as a fact that M$ frequently had apps make direct calls, *not* to the system, but directly to the hardware because the code ran so slowly. For example, the classic proof was when Apple went from Moto chips to PowerPC, and it broke Word, where they were doing just that (and I've heard that from friends who are Macaholics). mark