Path: utzoo!attcan!uunet!mailrus!ncar!boulder!hartzell
From: hartzell@boulder.colorado.edu (George Hartzell)
Newsgroups: comp.sys.mips
Subject: ls -A and the MIPS
Keywords: fasl, executable text space.
Message-ID: <14057@boulder.Colorado.EDU>
Date: 19 Nov 89 21:48:29 GMT
Sender: news@boulder.Colorado.EDU
Reply-To: hartzell@boulder.colorado.edu (George Hartzell)
Organization: University of Colorado, Boulder
Lines: 35


I am working on a port of ELK (a scheme interpreter) to our M2000
running RISCos 4.01 with the 2.10 beta compilers.  I have everything
but "dynamic loading" working (apparently this is also known as
fasl'ing).  Here is what the author says is required to support
CAN_DYNAMIC_LOAD.

   Dynamic loading:

      Define CAN_LOAD_OBJ if the target system enables dynamic loading
      of object files.  This requires that the system linker (/bin/ld)
      supports the -A and -T options for incremental loading and that
      the data space in the interpreter is executable, i.e. that it is
      possible to derive a function pointer to an object that has been
      loaded into data space.  In addition, it requires that your system
      supports the BSD-style a.out format; the current release of the
      software does not support dynamic loading for other a.out file
      formats (such as COFF).

I've written the support for the MIPS object format and Third Eye
symbol tables, and have ld -A -T working (after building G0 copies of
a library or two...).  I can read in the resulting OMAGIC file, and
can determine the address of a function that I want to call.  The
result is always a segmentation fault.  

Before I spend too much more time figuring out why this isn't working,
is there someone out there who can tell me IF IT IS POSSIBLE?  e.g.
can I call a function pointer that points into my data space?  Do I
have to do something special to do this?  Is it impossible?

Any help would be appreciated.
g.
George Hartzell			                  (303) 492-4535
 MCD Biology, University of Colorado-Boulder, Boulder, CO 80309
hartzell@Boulder.Colorado.EDU  ..!{ncar,nbires}!boulder!hartzell