DosCallback
Bindings: C, MASM
This call provides a privilege level 2 IOPL segment to call a privilege
level 3 application segment.
DosCallback (Ring3Routine)
Ring3Routine (PFN) - input
Address of the privilege level 3 application routine to be called.
Remarks
This function allows a routine executing with I/O privilege (at privilege
level 2) to call a segment that is executing at privilege level 3 and
also to have the target routine execute at privilege level 3; for
example, not to allow/require the target routine to be privilege level 2
conforming.
The requested routine is given control at privilege level 3 and when it
completes execution and returns, return is made to the privilege level 2
calling routine.
All registers except FLAGs are passed intact across this call return
sequence and may be used to pass parameters or data. Any addresses passed
from privilege level 2 to privilege level 3 must be based on privilege
level 3 selectors only as the privilege level 3 code does not have proper
addressability to any privilege level 2 data selectors.
The privilege level 2 stack can not be used to pass data to the privilege
level 3 routine.
If DosCallback is used in a nested fashion such that a privilege level 3
routine issues a call to a privilege level 2 routine while performing a
"Callback" operation (after being invoked by "Callback" but before having
issued a Far RET back to the privilege level 2 code), any subsequent
DosCallback requests must complete execution and issue their
corresponding Far RETs in last-in-first-out (LIFO) order.
Created using Inf-PHP v.2 (c) 2003 Yuri Prokushev
Created using Inf-HTML v.0.9b (c) 1995 Peter Childs