Hello Mike!

Thus quoth Mike Bilow to Rinat Sadretdinow:
 DE>> Nothing in OS/2 stops you from entering 32-bit segments and retaining
 DE>> IOPL privileges after you went through a 16-bit ring-2 callgate. The
 DE>> only problem is to set up or find a proper ring-2 32-bit code
 DE>> selector, but it's possible - rest assured.
 MB> Note that there is no way to make the necessary set up except from
 MB> Ring 0, in which case all of this is pointless.  Since OS/2 provides
 MB> a facility for loading a 16-bit segment with IOPL, and for calling
 MB> into such a 16-bit segment from a 32-bit segment, you should use the
 MB> provided facilities.

I repeat: running code in a 32-bit segment with IOPL *is possible*, I have
working code here. There is *no setup from ring 0* needed to do this. And I
do 'dirty tricks' like these despite IBM's intentions, because running
32-bit code at ring 2 compiled and debugged by the same toolset as ordinary
ring 3 code sounds much more convenient and useful to me than using
assembler or an old fashioned 16-bit C compiler, not to mention not being
limited by a 16-bit environment. And it saves a lot of development time if
your only need is to access some IO ports but don't require interrupts or
DMAs. Once I had to implement a driver to a DSP coprocessor board; it was
finished after 2 hours using these techniques - I expect a much longer
development time if I had to implement a full device driver.

bye, Detlef

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