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linking error undefined symbol _start

linking error undefined symbol _start

Post by Alex Tyrrel » Wed, 03 Jul 2002 06:38:42



I'm brand new at linux development, I'm currently having problems with
linker specifically that it creates the output file but issues a warning
that it couldn't find symbol _start ( I'm working with a very basic "hello
world" app).  Then I can't even run the resulting executable, oddly enough
the shell says the file doesn't exist.  I think this is a common problem and
I'm most interested in how it relates to ctr0.o because the ld man page
mentions it and I don't have one anywhere on my system red hat 7.1 kernel
2.4.18 smp.  Instead I have /usr/lib/crt1.o ../crtn.o crti.o.  I'm using gcc
3.0.4 and gnu ld 2.10.91.

As a quick rundown I do this-

gcc main.c -c -o main.o
ld -o main main.o -lc
warning: unresolved symbol _start

Incidentally if I try linking with /usr/lib/crt1.o,crti.i,crtn.o the warning
goes away but the exe still won't run correctly.

Alex

 
 
 
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linking error undefined symbol _start

Post by Stephane SOPPER » Wed, 03 Jul 2002 03:49:19


Quote:> gcc main.c -c -o main.o
> ld -o main main.o -lc
> warning: unresolved symbol _start

Actually you never runs ld directly:
you can do:
gcc -o main main.c
or in two steps:
gcc -c main.c (that will create main.o)
gcc -o main main.o (that will link the program)

for C++ replace gcc by g++

--
Stephane SOPPERA
http://stephane.soppera.free.fr

 
 
 
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linking error undefined symbol _start

Post by Eric P. McC » Wed, 03 Jul 2002 04:08:49



> ld -o main main.o -lc

Don't link with `ld', use `cc' or `c++' (whichever is appropriate).

--

"Last I checked, it wasn't the power cord for the Clue Generator that
was sticking up your ass." - John Novak, rasfwrj

 
 
 
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linking error undefined symbol _start

Post by Floyd Davidso » Wed, 03 Jul 2002 04:47:19



>> gcc main.c -c -o main.o
>> ld -o main main.o -lc
>> warning: unresolved symbol _start

>Actually you never runs ld directly:
>you can do:
>gcc -o main main.c
>or in two steps:
>gcc -c main.c (that will create main.o)
>gcc -o main main.o (that will link the program)

>for C++ replace gcc by g++

To make this interesting, in order to learn what ld does, try

  gcc -v -o main main.c

The linker called won't be ld, but to manually link a program
ld can be used with the identical command line.

--
Floyd L. Davidson         <http://www.ptialaska.net/~floyd>

 
 
 
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1. undefined symbol when linking bash

I'm trying to make bash 1.12 on an AT&T 3B2/400
running System V 3.2.2.  After a little tinkering
around, all the libraries and object files are done.
However, when it comes to link time, the make dies
with ....

        cc     -g -L./lib/readline/  -L./lib/glob/ \
           -o bash shell.o y.tab.o general.o make_cmd.o print_cmd.o   dispose_cmd.o execute_cmd.o variables.o copy_cmd.o error.o  expr.o flags.o jobs.o subst.o hash.o mailcheck.o test.o  trap.o alias.o ./lib/malloc/malloc.o  braces.o unwind_prot.o  siglist.o  version.o bashline.o builtins/libbuiltins.a -lreadline -ltermcap -lglob -lPW
undefined                       first referenced
 symbol                             in file
opendir                             ./lib/readline//libreadline.a
readdir                             ./lib/readline//libreadline.a
closedir                            ./lib/readline//libreadline.a
ld fatal: Symbol referencing errors. No output written to bash
*** Error code 13
`all' not remade because of errors

Earlier, the readline library wouldn't make until I snarfed a
sys/ndir.h file from another box (SCO).  (It was dying with references
to syntax errors on lines 5172 and 5257 of readline.c)  In case
it helps, here are those 2 lines:

  5172: static DIR *directory;

  5255:  {
  5256:  closedir (directory);
  5257:  directory = (DIR *)NULL;
  5258:  }

The 3 functions readdir, opendir, and closedir seem to have been
defined in the ndir.h file.  I also had to pull in sys/dirent.h
from another box, as the dirent.h on the AT&T box didn't have
DIR defined.  

Anyone know a way around these obstacles?

Thanks!
--
Randall W. Hron
Roswell, GA  USA
uunet!gatech!kd4nc!vdbsan!willard!hrandoz!hronr

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