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From: patterso@cs.scarolina.edu (Mitchell Patterson)
Newsgroups: comp.sys.mips,comp.unix.ultrix
Subject: ``jump relocation out-of-range''?
Summary: ld -A <base> -N -T <something> <object file>
Keywords: incremental loading, dynamic linking, confusion
Message-ID: <patterso.677975160@oak.cs.scarolina.edu>
Date: 26 Jun 91 22:26:00 GMT
Sender: usenet@usceast.cs.scarolina.edu (USENET News System)
Distribution: comp
Organization: USC  Department of Computer Science
Lines: 46

I'm trying to implement incremental loading on a DECstation 2100 under Ultrix
4.0, and that message about jump relocation is what I get when I try to set
the start of the text segment to an address that is some magic amount
higher than that of a function in the file I'm using as a base. What's the 
limit for a jump? A page boundary? Can I get around it? If so, does anyone
have any ideas?

Here's what I'm doing:

   (1) Compile the file test.c with the flag -G 0 set. That file contains
       the following:
          int foo()
          {
             puts("I'm here!");
          }
   (2) I have another program which does this:
          (a) Read the section headers for .text, .data, and .bss to get
              their sizes.
          (b) Add those sizes up and malloc that much memory. I believe
              malloc(3) claims that the memory it returns is suitably
              aligned for just about anything.
          (c) Issue this command:

       "ld -A <base program> -N -T <the address returned by malloc> test.o"

              The -N tells ld to make data follow text and to make text
              writeable, I believe; it may be a frill.
             
          (d) I sit for a little while, and then I get that message about
              jump relocation out of range. I've played with it a little,
              sending bogus values to -T like 48; the loader doesn't complain.

Since I'd like to use ld to handle the relocation instead of doing it myself,
I'd appreciate any advice anyone can give. I mainly need to know how to get
ld to relocate based on an arbitrarily-large (*) value for -T.

Thanks!

   Mitch

(*) since malloc will probably return high addresses?
--
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         I have 6 personalities, but they're all identical.
Mitch Patterson - eXpert eXplorer project - patterso@usceast.cs.scarolina.edu
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