Re: [cc65] Segment EXEHDR does not exist - while using ld65 directly

From: "Ullrich von Bassewitz"; on Tuesday, July 07, 2009; at 11:50 AM -0400
>
> On Tue, Jul 07, 2009 at 04:59:49PM +0200, Jakub wrote:
> > Test 2:
> > cc65 -T -Osir --cpu 6502 -t atari test.c
> > ca65 -l -t atari test.s
> > ld65 -t atari test.o atari.lib -o test2.xex
> > ld65.exe: Warning: [builtin config](15): Segment `EXEHDR' does not exist
> > ld65.exe: Warning: [builtin config](25): Segment `AUTOSTRT' does not exist
>
> You are not linking the start-up code into the executable.
>
> > What is strange, after adding function call without a prototype
> > (which generates warning), it works:
> >
> > #include <stdio.h>
> > int main(void)
> > {
> >   printf("Test\n");
> >   exit(0); // <- without a prototype. xex file is generated fine!
> >   return 0;
> > }
>
> That's not really strange:  The exit() function is a part of the start-up
> code [because, returning from main() is like calling exit()].  So, when
> calling exit(), you actually do generate a dependency to the start-up
> code, and the linker will include it.  That, in turn, fixes the above error
> messages.

That reminds me of an idea:
When the C compiler sees the definition of main(), it inserts a
".forceimport" line into its assembly-code output if that main() has
parameters.  I think that it will be useful for the compiler to generate
another ".forceimport" line when it sees main() { }:

    .forceimport    _exit

That will ensure that the start-up code is linked when it is needed -- we
won't need to remember to link the start-up file.  In fact, we won't need a
_separate_ file; the copy of it that is inside the library file will be
enough.

If you accept that idea, then it must be put on your "to-do" list because
it needs STARTUP segment support (to guarantee where the code is put).
Some of the targets do not have that segment -- yet.

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