Re: [Freedos-devel] BIOS calls in 16bit protected mode

[Ladislav L. <la...@se...>]

I think generaly BIOS interrupts can be called from 16-bit protected mode in case when all interraction between BIOS and user program is done using registers. If the interraction is done via buffers, it will not work.

> ------------ Původní zpráva ------------
> Od: Bret Johnson <bre...@ju...>
> Předmět: Re: [Freedos-devel] BIOS calls in 16bit protected mode
> Datum: 14.6.2012 16:16:29
> ----------------------------------------
> > Specifically, I am trying to determine if there are legacy
> > applications or operating systems that invoke standard BIOS
> > real-mode interrupt handlers while in 16bit protected mode.  (The
> > legacy real-mode entry points - like "int 0x13" - not the
> > declared 16bit protected mode entry points defined by the PnP and
> > APM specs.)
> 
> I am currently i process of updating my USB TSR drivers so that they can run int
> 16-bit protected mode, with the aid of the Novell-provided DPMS server.  When I
> need to issue a BIOS INT call of some sort from inside the TSR, however, I
> currently do not do it with an "INT xx" OpCode.  Instead, I look up the vector
> address in the IVT and issue a DPMS "Call Real Mode Procedure with IRET"
> function.
> 
> I could theoretically issue the "INT xx" OpCode directly, but I don't do it that
> way for logistical reasons, at least in the current versions of the programs --
> but that could change in the future.  In short, I think what you're doing is
> probably not a good idea.  It's not just "legacy" applications you need to worry
> about, but new ones (including TSR's and Device Drivers) as well.
> 
> I think Japheth's JLM architecture for TSR's and Device Drivers allows them to
> do things from 16-bit PM as well, though the "default" is 32-bit PM. 
> 
> 
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