[Bug ld/21459] Wrong location for .debug_gdb_scripts on Windows

[egonelbre at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=21459

--- Comment #11 from Egon Elbre <egonelbre at gmail dot com> ---
(In reply to Nick Clifton from comment #10)
> Hi Egon,
> 
> (In reply to Egon Elbre from comment #8)
> 
> > I'm wondering whether Wine or ReactOS will fail with that executable?
> 
> Maybe - I could also set up a proper MinGW or Cygwin environment.  The
> real problem is time - I just do not have enough of it to spend on these
> bugs. :-(

Sure, I understand.

> 
> > Do you see the same result with objdump?
> 
> Oh yes - I just thought that the non-zero VMA value would be enough.  I did
> not know that there was going to be a problem with large gaps between parts
> of the program and/or excessively large VMA values.
> 
> > Sure, if it seems too much work it's fine to include in the script.
> 
> I have gone ahead and done that.  It is a simple, easy fix that will let you
> get on with your work for now.
> 
> > Maybe there's a good place to put an ASSERT bomb when it tries to write VMA
> > 0xFFFFFFFFLL or zero?
> 
> Probably.  Although I would love to know if it is the high VMA address that
> is causing the problem, or the gap between the two parts of the program that
> is causing the problem.  (We are talking 64-bit binaries here, right ?)

After testing some more it seems that when you set the VMA=0x0, then objdump
will show it as 0x100000000. I'm not sure whether it's intentional (per spec)
or not (an underflow).

After searching about gap issues in PE, I found these:

https://github.com/msekletar/sbsigntool/blob/a6043253a4f8621b8eac0fd099e26a8a992cb13a/src/image.c#L331

https://stackoverflow.com/questions/32378033/why-does-section-virtual-addresses-need-to-be-continuous

Few links later I found PE/Coff spec, which says:

  In an image file, the VAs for sections must be assigned by the 
  linker so that they are in ascending order and adjacent, and 
  they must be a multiple of the SectionAlignment value in the 
  optional header.

and also...

  In an image file, the section data must be aligned on a boundary 
  as specified by the FileAlignment field in the optional header. 
  Section data must appear in order of the RVA values for the 
  corresponding sections (as do the individual section headers 
  in the section table).

And after ensuring that sections are adjacent, executable manages to start.

Cheers
  Egon

> 
> Anyway, I will leave this PR open, but I am not expecting to be able to give
> it a lot of time unless it becomes a real show-stopper for someone.
> 
> Cheers
>   Nick

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