Re: extending elf32-i386 BFD backend

[Daniel Jacobowitz <drow at mvista dot com>]

On Fri, Mar 22, 2002 at 12:42:12PM -0500, Graeme Peterson wrote:
> Hi, all.
> 
> I'm working on the i386-pc-nto-qnx support for binutils.
> QNX now has Copyright Assignment, and the ntox86 support 
> is ready for submission, with one exception.
> 
> Throughout elf.c, there are checks to see if a segment
> is loadable (or not):
> 
> 	if (segment->type == PT_LOAD)
> 
> or
> 
> 	if (phdr->p_type == PT_LOAD)
> 
> QNX6 has 2 other loadable ptypes defined in our sys/elf.h
> 
> 	PT_COMPRESS = 0x4000 
> 	PT_SEGREL   = 0x4001
> 
> Nick Clifton has been very helpful (Thanks Nick!), and suggests
> I add a new BFD backend function, and then have a macro in 
> bfd/elf.c :
> 
> 	#define IS_LOADABLE_SEGMENT(abfd, seg, bed)     \
> 	  (bed->is_loadable_segment                     \
> 	   ? bed->is_loadable_segment (abfd, seg)       \
> 	   : (seg)->type == PT_LOAD)
> 
> The only way (I think) I know to do that is to copy elf32-i386.c, 
> rename it to something like elfqnx-i386.c, add the BFD backend 
> extension, and put the support in config.bfd, Makefile.in, targets.c...
> (I have never added a new BFD backend, so the above may not be
> right).

The general way to do this is in BFD is:
  - prefix the definition with #ifndef IS_LOADABLE_SEGMENT
  - Create elfqnx-i386.c which defines it and #include "elf32-i386.c"

(Not the cleanest design, perhaps, but it's what we've got right
now...)

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer