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From: "Ralf Habacker" <Ralf DOT Habacker AT saght DOT tessag DOT com>
To: <cygwin AT cygwin DOT com>
Subject: problems with --export-all-symbols option
Date: Thu, 19 Apr 2001 15:34:41 +0200
Message-ID: <003001c0c8d5$7d0d3260$6e032bb7@BRAMSCHE>
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Hi,

I like to use the --export-all-symbols option to create a dll with all
symbols exported how I found in the online documentation of gcc
But this results in a linker failure, which says that some symbols
"_[bss|data]_[start|end]__" not found.
Additional in the resulting .a file the global variable is left.

By the way I'm using gcc version 2.95.3-2 (cygwin special).

I have added an example for this problem.

foo.h -----------------

extern int testvar;
int testfunc(int a);

foo.c -----------------

#include <stdio.h>
#include "foo.h"

int testvar = 0;

int testfunc(int a)
{
        printf("%d\n",a);
        return 0;
}

making... ----------------------------

gcc -c foo.c -o foo.o
gcc -v -shared -Wl,--export-dynamic -Wl,--output-def=libfoo.def \
        -Wl,--out-implib=libfoo.dll.a -Wl,--enable-auto-image-base \
        --export-all-symbols -o libfoo.dll foo.o
Reading specs from /usr/lib/gcc-lib/i686-pc-cygwin/2.95.3-2/specs
gcc version 2.95.3-2 (cygwin special)
 /usr/lib/gcc-lib/i686-pc-cygwin/2.95.3-2/collect2.exe --shared -Bdynamic -e
__cygwin_dll_entry AT 12 --dll-search-prefix=cyg -o

libfoo.dll -L/usr/lib/w32api -L/usr/local/lib -L/usr/lib -L/usr/lib/gcc-lib/
i686-pc-cygwin/2.95.3-2 --export-dynamic --outpu
t-def=libfoo.def --out-implib=libfoo.dll.a --enable-auto-image-base
foo.o -lgcc -lcygwin -luser32 -lkernel32 -ladvapi32 -lshe
ll32 -lgcc
Cannot export _bss_end__: symbol not defined
Cannot export _bss_start__: symbol not defined
Cannot export _data_end__: symbol not defined
Cannot export _data_start__: symbol not defined
Creating library file: libfoo.dll.a
collect2: ld returned 1 exit status
make: *** [libfoo.dll] Error 1

The resulting def file looks like this: -------------
EXPORTS

    GetModuleHandleA AT 4 @1 DATA
    __CTOR_LIST__ @2 DATA
    __DTOR_LIST__ @3 DATA
    _bss_end__ DATA
    _bss_start__ DATA
    _cygwin_crt0_common AT 8 @4 DATA
    _cygwin_dll_entry AT 12 @5
    _cygwin_noncygwin_dll_entry AT 12 @6
    _data_end__ DATA
    _data_start__ DATA
    _fmode @7 DATA
    _head_libkernel32_a @8 DATA
    _head_templib_a @9 DATA
    _imp__GetModuleHandleA AT 4 @10 DATA
    _imp__calloc @11 DATA
    _imp__cygwin_detach_dll @12 DATA
    _imp__cygwin_internal @13 DATA
    _imp__dll_dllcrt0 @14 DATA
    _imp__free @15 DATA
    _imp__malloc @16 DATA
    _imp__printf @17 DATA
    _imp__realloc @18 DATA
    _impure_ptr @19 DATA
    calloc @20 DATA
    cygwin_attach_dll @21 DATA
    cygwin_detach_dll @22 DATA
    cygwin_internal @23 DATA
    cygwin_premain0 @24 DATA
    cygwin_premain1 @25 DATA
    cygwin_premain2 @26 DATA
    cygwin_premain3 @27 DATA
    dll_dllcrt0 @28 DATA
    environ @29 DATA
    free @30 DATA
    libkernel32_a_iname @31 DATA
    malloc @32 DATA
    printf @33 DATA
    realloc @34 DATA
    templib_a_iname @35 DATA
    testfunc @36
    testvar @37 DATA

$ nm libfoo.dll.a | grep "T _"
00000000 T _testfunc
00000000 T __cygwin_noncygwin_dll_entry AT 12
00000000 T __cygwin_dll_entry AT 12

$ nm libfoo.dll.a | grep "testvar"
00000000 I __imp__testvar


Has anyone an idea what I can do to solve the problem ?

Thanks

Ralf Habacker
Germany


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