Re: Forth for Mac OS X Leopard (Intel) - what are the options?

Albert van der Horst <albert@[EMAIL PROTECTED]
> wrote:
> In article <vjrLj.662$Ms6.496@[EMAIL PROTECTED]
>,
> Josh Grams  <josh@[EMAIL PROTECTED]
> wrote:
>>
>>But the linker only looks for the normal sections, so if you want to use
>>different section names, you have to write a linker script.  These can
>
> In my experience the gnu linkers just put my out-of-the-ordinary
> sections in a reasonable place. The only crucial point is to have
> a _start global symbol somewhere. The linker script has a default
> place for extra sections.

Ah, so it does.  Thanks for the correction.  I could swear I had trouble
with this at some point, but maybe I was trying to do something
trickier.  Or maybe it was an early Linux PPC binutils; they were pretty
buggy for a while.

>>Usually executables have the same structure in memory as in the file
>>(though often there is a gap between code and data).  And usually the
>>headers are also mapped into memory.  So to SAVE-SYSTEM, you just have
>>to know where the headers are, store the new (larger) sizes, and then
>>write everything out to a file.
>
>This is almost exactly how the SAVE-SYSTEM in lina works. The elf headers
>contain references to things that are not important. Specify that there
>are zero of those, and nobody will try to read them.
>There is little value or portability in lina's SAVE-SYSTEM so it is
>not worthwhile to try to use elf on OSX just to use it.
>The same tricks are applicable to OSX executable headers.

Yeah, I was reading lina's SAVE-SYSTEM.  I didn't take the time to
understand all the details, but it looked like that was what it did.

It might be a bit trickier on OSX, as it's (sort of) BSD underneath.  I
was helping port IsForth to FreeBSD, and we had to put in .text and
..data (and maybe .bss) sections for it to run.  IsForth uses brk()
instead of the ELF headers to allocate blank memory for the dictionary;
without that we might not have needed the .data section.  But FreeBSD
was definitely much more picky than Linux.

--Josh