Hallo, Denis!

*** Am 30. September 1998 um 13:20 schrieb Denis Tonn an Jonathan de Boyne Pollar:

 DT>  Callbacks from Ring 0 back to Ring 3 do exist. Exception and Exit
 DT> handlers, along with DLL InitTerm are examples. The Ring 3 stack is
 DT> setup to have an address in Doscall1 that will reenter Ring 0 using a
 DT> particular callgate, then a stack frame is built on the Ring 0 stack
 DT> that "looks" (to the CPU) as though the kernel is
"returning" through
 DT> a callgate. The return instruction causes the CPU to restore the
 DT> application's ring 3 stack.

This is very interesting! Thank you for opening that secret little box :-)

The paragraph quoted above seems to imply there is a callgate that refers
more or less directly to a return instruction, does it?


Tschau...Thomas

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