Date: Mon, 14 Jul 1997 09:33:11 +0000
From: Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
Subject: Re: ANNOUNCE: bcsio20.zip - serial comms package.
To: Hartmut Schirmer <hsc AT techfak DOT uni-kiel DOT de>
Cc: djgpp AT delorie DOT com
Reply-to: billc AT blackmagic DOT tait DOT co DOT nz
Message-id: <33C9F257.75F3@blackmagic.tait.co.nz>
Organization: Tait Electronics NZ
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References: <199707102224 DOT SAA06012 AT delorie DOT com>
 <33C5EADC DOT 79A AT techfak DOT uni-kiel DOT de>
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Hartmut Schirmer wrote:
> 
> Bill Currie wrote:
> > Non-features:
> >  * Does NOT work under windows 3.x (due to the cli bug in windows)
> 
> Bill,
> could you explain this bug ?

If you disable interrupts, it can (not always, but usually) become
impossible to re-enable them.  `real mode' programs work fine because
they run with iopl=3 (they have direct access to the hardware interrupt
flag) but protected mode programs have iopl=2 but still run in ring 3,
and access to the interrupt flag is emulated (iopl nned to be 2 so the
ports can be virtualised in protected mode (the ports are always
virtualised when the cpu is in v86 mode, so the iopl can be 3)).

Bill
-- 
Leave others their otherness.