On Sun, 03 Sep 2000, brian moore wrote: > On Mon, Sep 04, 2000 at 12:25:57AM -0400, Mark Simos wrote: > > As I understand it, X86 hardware hardly ever uses anything but two levels. I know sun > > hardware actually makes significant use of the runlevels, but I am made to understand > > that nobody ever really bothered to implement any more than two different runlevels. > > > > (I think this is similar to windows progs running in user or kernel mode (ring 0 or > > ring [2?] of x86 processors) > > > > does anybody have anything besides hearsay to confirm or deny this? [snip -- nice explanation on sysv runlevels] As for the user or kernel mode (the "hardware runlevels"), linux uses only 2: it uses ring 0 (kerneland ;-) ) and ring 3 (userland). Other ring levels (1 & 2) aren't used because it takes just too much time to switch rings in most (all?) x86 CPUs... They'd be useful for kernel drivers if not for this fatal drawback. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh
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