From: cjensen AT ampex DOT com (Colin Jensen)
Subject: Re: OS/2
To: sandmann AT clio DOT rice DOT edu (Charles W. Sandmann)
Date: Fri, 30 Jul 93 9:58:44 PDT
Cc: MFINE AT delphi DOT com, djgpp AT sun DOT soe DOT clarkson DOT edu


> >   Does anyone know of a GCC port to OS/2?  Or better yet, has anyone got a
> > cross-compiler setup to target OS/2 from UNIX?  

Currently, there is no supported way of compiling an OS/2 program on UNIX.
I think that if you put some effort into it, you could create a version
of the EMX/GCC compiler that could do this.

The other OS/2 gcc (called gcc/2) cannot be converted into a UNIX->OS/2
cross compiler since it requires the linker that comes with OS/2, link386.

> There are at least 3 ways to use GCC with OS/2 (which I have done all of...)
>  1) Use DJGPP in a DOS box with the DPMI support.  Believe it or not, for
>     character cell applications this is FASTER than native OS/2 code, since
>     you don't have to thunk to the 16 bit OS/2 stuff each time you want to
>     write a string.

The is not quite correct.  The reason DOS command line boxes are faster
than OS/2 command line boxes is that each character output from an OS/2
box is updated immediately, and scrolling speed is awful.  The window
of a DOS box is updated fully only every tenth of a second - which
essentially provides a jump scroll feature (i.e. several real scrolls can
be converted into a single multi-line scroll on screen).  A full-screen
OS/2 box is *much* faster than a full-screen DOS box under OS/2.

If anyone is serious about using djgpp under OS/2, I would suggest that
they compile djgpp using one of the two OS/2 gcc compilers; thereby
creating an OS/2 -> DOS djgcc cross compiler.  This compiler would be
tons faster than the DOS djgcc since it wouldn't have to hassle with
getting in and out of real mode to perform I/O.

>  2) Get a copy of EMX (hobbes.unm.edu (or somesuch)) is a great place to get
>     lots of OS/2 software, including ports with GCC.  EMX also will run under
>     DOS, and has many nice features.  It does not include all source, however,
>     which makes it unsupportable long term in a commercial environment.  

Specifically, the source code of EMX's DOS/OS/2 extender is not provided.
However, look also at the license conditions for programs that run on the
EMX extender carefully.  Depending on your company's attitude, this could
be a problem.

The output of the gcc/2 compiler is entirely free of restrictions other
than your own.  (So long as you don't use the GNU C++ Libraries)

>  3) There is a GCC port on charon.mit.edu (official I think?) which has some
>     problems but carries much less baggage than the EMX version.

The version of gcc on charon.mit.edu is a *year* out of date.  The
place to get both EMX/GCC and gcc/2 is at `ftp-os2.cdrom.com' in the
directory pub/os2/2_x/unix/gnu/emxXXX and pub/os2/2_x/unix/gnu/gcc2_233.
Neither compiler is more "official" than the other.

EMX/GCC is the more mature product, as long as you can live without
full source and can live with the license.

-- 
Colin Jensen
cjensen AT ampex DOT com