RE: Dynamic Linking

Here's a script to test the type of library used by a program.  It was
written by an engineer here at Transcept.  I'll let him take credit
personally
if he wants to.

jeff

		#!/bin/sh

		if test $# = 0; then
		  echo Usage: xfile FILE ...
		  exit
		fi

		for i in "$@"; do
		 echo -n "$i: "
		 
		 if test -f "$i"; then
		  :
		 else
		  echo "doesn't exist"
		  continue
		 fi

		 if file "$i" 2>&1 | grep -q "dynamically linked"; then
		  echo -n "Dynamically linked "
		 elif file "$i" 2>&1 | grep -q "statically linked"; then
		  echo -n "Statically linked "
		 else
		  echo "Not an executable"
		  continue
		 fi

		 if readelf -S "$i" 2>&1 | grep -q "\.note\.ABI-tag";
then
		  echo "with GNU Libc 2"
		 else
		  echo "with old Libc"
		 fi
			done

----- Original Message -----
From: "Grant Carter" <redacted>
To: "linuxppc-embedded" <redacted>
Sent: Monday, January 17, 2000 9:23 AM
Subject: Dynamic Linking

quoted

Hi

I have been following the thread "Cross-compile Applications for 860

on

quoted

x86" and am running into similar problems. I have tried the

solutions

quoted

that have been suggested but have had no success. Perhaps those
concerned have had private email conversations in which the solution

has

quoted

been found, but since I cannot find one in the archives that helps

me,

quoted

I'll post this question. Apologies for its length.

I am trying to get a hello world up and running using dynamically

linked

quoted

libraries. The statically linked version works fine, so I presume

that

quoted

the libraries are all fine. I am using linux-2.2.13 with no kernel
floating point support, but all the libraries and executables are
compiled with -msoft-float. I am using SASH-2.1 and it works fine.

My

quoted

problem is that whenever I run something that I have compiled with

the

quoted

dynamic linker, it exits on Signal 11.

I have made sure that LD_LIBRARY_PATH is set to /lib (it seems that

I

quoted

had to do this even though all my libraries are in /lib as without

it I

quoted

get a

./hello: error in loading shared libraries: libc.so.6: cannot open
shared object file: No such file or directory

Doing a "strings" on the file shows that it is looking in /lib for
ld.so.1.)

---------------------------------

quoted

powerpc-linux-strings hello

/lib/ld.so.1
__gmon_start__
libc.so.6
printf
_IO_stdin_used
__libc_start_main
GLIBC_2.0
}a[xN
Grant was here!
-----------------------------------

Anyhow, once the LD_LIBRARY_PATH has been set, the libraries are

loaded

quoted

(or so it seems) Now everything that I run exits with Signal 11. I

used

quoted

objdump -p on the main executable and saw that it required

libc.so.6.

quoted

This exists in my /lib directory
-----------------------------------

quoted

powerpc-linux-objdump -p hello

hello:     file format elf32-powerpc

<snip>

Dynamic Section:
  NEEDED      libc.so.6
  INIT        0x100003c8
  FINI        0x100003ec
  HASH        0x10000150
  STRTAB      0x100001c8
  SYMTAB      0x10000178
  STRSZ       0x42
  SYMENT      0x10
  DEBUG       0x0
  PLTGOT      0x100104f8
  PLTRELSZ    0x18
  PLTREL      0x7
  JMPREL      0x10000240
  RELA        0x10000240
  RELASZ      0x18
  RELAENT     0xc
  VERNEED     0x10000220
  VERNEEDNUM  0x1
  VERSYM      0x10000214

Version References:
  required from libc.so.6:
    0x0d696910 0x00 02 GLIBC_2.0
-----------------------------------

Doing the same thing on libc.so.6, I get the following:

-----------------------------------

quoted

powerpc-linux-objdump -p libc.so.6

libc.so.6:     file format elf32-powerpc

Program Header:
<snip>

Dynamic Section:
  NEEDED      ld.so.1
  SONAME      libc.so.6
  INIT        0x21cb8
  FINI        0xe0fc8
  HASH        0xf4
  STRTAB      0x9d0c
  SYMTAB      0x2cdc
  STRSZ       0x7ca2
  SYMENT      0x10
  PLTGOT      0x103a9c
  PLTRELSZ    0x150c
  PLTREL      0x7
  JMPREL      0x204d8
  RELA        0x128c4
  RELASZ      0xf2dc
  RELAENT     0xc
  VERDEF      0x127e0
  VERDEFNUM   0x5
  VERNEED     0x12884
  VERNEEDNUM  0x1
  VERSYM      0x119da

Version definitions:
1 0x01 0x0865f4e6 libc.so.6
2 0x00 0x0d696910 GLIBC_2.0
3 0x00 0x0d696911 GLIBC_2.1
        GLIBC_2.0
4 0x00 0x09691f71 GLIBC_2.1.1
        GLIBC_2.1
5 0x00 0x09691f72 GLIBC_2.1.2
        GLIBC_2.1.1

Version References:
  required from ld.so.1:
    0x09691f71 0x00 08 GLIBC_2.1.1
    0x0d696911 0x00 07 GLIBC_2.1
    0x0d696910 0x00 06 GLIBC_2.0
-----------------------------------

And now for ld.so.1

-----------------------------------

quoted

powerpc-linux-objdump -p ld.so.1

ld.so.1:     file format elf32-powerpc

Program Header:
<snip>
Dynamic Section:
  SONAME      ld.so.1
  HASH        0x94
  STRTAB      0x838
  SYMTAB      0x2f8
  STRSZ       0xcfc
  SYMENT      0x10
  PLTGOT      0x25fd4
  PLTRELSZ    0x12c
  PLTREL      0x7
  JMPREL      0x2ab0
  RELA        0x167c
  RELASZ      0x1560
  RELAENT     0xc
  VERDEF      0x15fc
  VERDEFNUM   0x4
  VERSYM      0x1554

Version definitions:
1 0x01 0x0275a261 ld.so.1
2 0x00 0x0d696910 GLIBC_2.0
3 0x00 0x0d696911 GLIBC_2.1
        GLIBC_2.0
4 0x00 0x09691f71 GLIBC_2.1.1
        GLIBC_2.1
-----------------------------------

So in summary, it seems that I have all of the required libraries
(ld.so.1 and libc.so.6) in the right place (/lib) as pointed to my
LD_LIBRARY_PATH and still I get a Signal 11 exit when trying to run

it.

quoted

Any ideas would be greatly appreciated.

Regards
Grant

--
Grant Carter                              gcarter@eng.uct.ac.za
Department of Electrical Engineering      University of Cape Town
Tel: +27 (0)21 650-3467                   Fax: +27 (0)21 650-3465
                     "Coffee not found - operator halted!"

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