[Elftoolchain-developers] Multiple archs and platforms.

[Chris J. <ch...@rt...>]

Hello,

I am developing a linker for the RTEMS project to support dynamic 
loading. I have just switched from the GPL libelf to your libelf after 
taking a look in the FreeBSD kernel. I am pleased to report there are no 
problems with the testing I have done. Our use of libelf is fairly basic.

You can find the RTEMS project at http://www.rtems.org/ and the linker's 
code is:

 
http://www.rtems.org/ftp/pub/rtems/people/chrisj/rtl/rtl-host-20111121.tar.bz2

To build install waf and then 'waf configure build'.

I plan to submit clean patches once I have the work completed.

I have copied in just the libelf and common directories. The code is 
built using waf and I can currently build on Linux (CentOS5), MacOS 
(Snow Leopard) and FreeBSD (v9). Windows is a work in progress and the 
reason for the post.

Some background. RTEMS supports around 12 architectures and all are ELF 
based. We need something to play with ELF files at a container level. 
The linker uses files, sections, and symbols and not much else. The low 
level target specific code is located in RTEMS and runs on the target 
hardware. So far I can handle SPARC, M68K and i386 ELF files on MacOS 
with the same executable. I do not expect problems in the other host 
operating systems.

Windows is a little more difficult to support. The couple of issues I 
have so far are:

1. Includes such as "#include <sys/errno.h>", and "#include 
<sys/cdefs.h>" are not supported. I have worked around this issue with a 
win32 specific include directory that maps to the standard headers in my 
application.

2. There is no mmap call. I see:

   LIBELF_F_RAWFILE_MALLOC | LIBELF_F_SPECIAL_FILE

could be used but I am not sure about a couple of things. Does this read 
the whole ELF file into memory ? Secondly, I really do not like the idea 
of __WIN32__ all over the place. I can support "HAVE_CONFIG_H" and 
"HAVE_MMAP" etc. How should I handle this ?

Any guidance or suggestions would be most welcome.

Chris