Date:	Mon, 3 Oct 94 10:33:53 +0100
From:	gwj AT J-23 DOT p DOT lodz DOT pl (Grzegorz Jablonski)
To:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	real mode callback - FAQ

Hi!
This message is addressed to Dong Liu (regarding his mouse callback
problem) and to all users of real-mode callback. This question becomes
a FAQ now. 
In Real mode callbacks DO NOT enable() and DO disable().
Doing so in mouse callback causes, that it works flawlessly. 
Why it works with both the instruction above under real DPMI?
1. DPMI specyfication says, that callbacks are called with interrupts
disabled. That is not true in case of go32 simulated DPMI.
2. Under DPMI sti and cli may be virtualized. It means, that they last
long (require two task switches) and may not really enable or disable
interrupts (disabling interrupts in multitasking environment may be
really harmful.
                             Grzegorz W. Jablonski

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