Date: Mon, 21 Aug 2000 14:41:28 +0200
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
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To: djgpp AT delorie DOT com
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	(marksmanANTISPAM AT adr DOT dk)
Subject: Re: How do I customize libc for custom OS?
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> From: "Tobias Skytte" <marksmanANTISPAM AT adr DOT dk>
> Newsgroups: comp.os.msdos.djgpp
> Date: Mon, 21 Aug 2000 11:38:45 +0200
> 
> I have just downloaded DJGPP, read the FAQ and some of the docs, I am new to
> C but experienced in Pascal (is that a bad word in this group? :-) )
> Basically I am writing a custom OS for i386+ in pmode, and I currently can't
> decide wether to use DJGPP or FreePascal (FPK). Now, one of the deciding
> factors is going to be: how easy is it to customise the compiler (libc in
> DJGPP, RTL in FPK) to work with a currently non-existing os (mine).?

I don't know anything about FPK; what's below relates to DJGPP only.

You need to replace the low-level library functions which interface
with the OS.  Basically, search for all the occurences of __dpmi_int
and int86, and you will find these functions.

The library startup code (crt0.S) will have to be rewritten as well,
since it is tailored to the DPMI environment.  Exception-handling
code, which is also the basis for signal support, will also need to be
reviewed.

If you want debug support, the functions in src/debug/common will also
have to be rewritten.

> Also: If someone could show me the compiler switches to compile a MZ EXE (my
> kernel will be in this format) without having the stub program

There are no switches for that; GCC and GNU Binutils don't support DOS
EXE format directly.  You might want to consider using the Windows PE
format, which *is* supported by GNU Binutils.

> Or how to make a straight binary (i.e. non-relicateable) which is
> another option for my kernel to be in.

You might try the binary format supported by Binutils.