Date: Mon, 21 Feb 94 14:17:13 JST
From: ishikawa AT personal-media DOT co DOT jp (Chiaki Ishikawa)
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Cc: garym AT argos DOT rose DOT utoronto DOT ca
Subject: Cross Compiling
Reply-To: ishikawa AT personal-media DOT co DOT jp

PMC e-mail id: 1514

Gary Lawrence Murphy wrote:
>How about the inverse problem: Is it possible to compile a unix GCC
>to cross-compile for the go32/MsDOS?

Yes, it is possible. I once ported a cross DJGCC compiler to a sparc
platform. 

The reverse problem requires (reverse) work. 

1. Some of the patches in the old DJGPP distribution were not
present in the FSF GNU distribution. So these have to be manually
edited in. (Not difficult since the DJGPP change was distributed in
patch form. You just run 'patch'.

2. The other difficult task is that the DJGPP distribution uses
certain batch files (*.bat) to modify existing machine dependent
files. You have to see which files are changed, appended, etc.. by
looking at the batch files (or better still, first see the output of
these batch run on DOS platform. This is the reverse of creating
suitable batch file from the run of shell script when you prepare
DOS-based cross compiler.).
You then have to either create a batch file to automate the process,
or simply prepate changed files manually.

This step is easily forgotten. But somehow, cross compiler generated
code seemed to work without these careful patches. I am quite sure
correct patches are necessary for reliable object code generation,
though.

3. A hacking to config script would be necessary so that [34]86-DOS
configuration is recognized by the autoconfig feature.

My experience is based on GCC 2.4.5 and DJGPP 1.09.


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     Chiaki Ishikawa                      Phone:+81-3-5702-0351
    Personal Media Corp.                   FAX:+81-3-5702-0359
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