LD problem

LD problem

[Krisztian Kocsis]

Hello!

I have a link dependency problem. If I try to link an application with
an .so file (exc. -lssl) the linker wants to link all its dependency
libraries not just libcrypto.so but libdl.so and libz.so also.

The toolchain is a crosstool-ng toolchain consists of:
- binutils-2.21
- gcc-4.5.3
- eglibc-2.14

If I add -Wl,--as-needed it does not help. There are still references in
the NEEDED entry for these libraries. I'v checked but there are no
referenced symbols from these libraries.

Do somebody know how can I restore the normal workflow, is any
configure option or something else?

BR,
Krisztian Kocsis

Re: LD problem

[Alan Modra]

On Sun, Jul 03, 2011 at 02:53:18PM +0200, Krisztian Kocsis wrote:
> Hello!
> 
> I have a link dependency problem. If I try to link an application with
> an .so file (exc. -lssl) the linker wants to link all its dependency
> libraries not just libcrypto.so but libdl.so and libz.so also.
> 
> The toolchain is a crosstool-ng toolchain consists of:
> - binutils-2.21
> - gcc-4.5.3
> - eglibc-2.14
> 
> If I add -Wl,--as-needed it does not help. There are still references in
> the NEEDED entry for these libraries. I'v checked but there are no
> referenced symbols from these libraries.

I think it most likely you have missed some reference.  Run ld under
gdb with a breakpoint on one of the following lines in elflink.c
	      add_needed = TRUE;
	      ret = elf_add_dt_needed_tag (abfd, info, soname, add_needed);
Examine "h".

> Do somebody know how can I restore the normal workflow, is any
> configure option or something else?
> 
> BR,
> Krisztian Kocsis

-- 
Alan Modra
Australia Development Lab, IBM

Re: LD problem

[krisztian.kocsis]

Hello!

In the meanwhile I'v discovered that ld (or gcc driver) turns on the
--no-allow-shlib-undefined option. I haven't discovered the reason
(I'v checked the patches, etc. - no success) but if I add the
-Wl,--allow-shlib-undefined (ld's man page says that this is the 
default
but it seems that the opposite is the default) it corrects the 
behavior.

Thanks for the help!

BR,
Krisztian Kocsis

On Mon, 4 Jul 2011 10:24:16 +0930, Alan Modra wrote:
> On Sun, Jul 03, 2011 at 02:53:18PM +0200, Krisztian Kocsis wrote:
>> Hello!
>>
>> I have a link dependency problem. If I try to link an application 
>> with
>> an .so file (exc. -lssl) the linker wants to link all its dependency
>> libraries not just libcrypto.so but libdl.so and libz.so also.
>>
>> The toolchain is a crosstool-ng toolchain consists of:
>> - binutils-2.21
>> - gcc-4.5.3
>> - eglibc-2.14
>>
>> If I add -Wl,--as-needed it does not help. There are still 
>> references in
>> the NEEDED entry for these libraries. I'v checked but there are no
>> referenced symbols from these libraries.
>
> I think it most likely you have missed some reference.  Run ld under
> gdb with a breakpoint on one of the following lines in elflink.c
> 	      add_needed = TRUE;
> 	      ret = elf_add_dt_needed_tag (abfd, info, soname, add_needed);
> Examine "h".
>
>> Do somebody know how can I restore the normal workflow, is any
>> configure option or something else?
>>
>> BR,
>> Krisztian Kocsis

Re: ld problem

[amodra]

On Sun, Apr 29, 2001 at 08:24:11PM -0400, Robert Schweikert wrote:
> 
> The EXTERN statements are all I have in the linker script, is this
> insufficient?

Hmm, I've never tried such a cut-down linker script.  I suspect that
omitting a SECTIONS command won't work very well.  I suggest you copy
the appropriate system link script (from $prefix/$target/lib/ldscripts
where $prefix and $target are the values you gave when configuring
binutils), and modify it.  See the comment around line 75 of
ld/genscripts.sh if you don't know which script to choose.

Alan

Re: ld problem

[Robert Schweikert]

On Sun, 29 Apr 2001 amodra@one.net.au wrote:

> On Mon, Apr 23, 2001 at 10:26:23AM -0400, Robert Schweikert wrote:
> >
> > Now if I use the same link command with the exception of replacing the
> > link script name with a -u uexternaldb_ everything works as expected.
> > What am I messing up here?
>
> Possibly just the location of your `EXTERN' statements.  Put them near
> the start of your linker script.
>
> Alan Modra
>
Alan,

The EXTERN statements are all I have in the linker script, is this
insufficient?

Thanks,
Robert

Robert Schweikert                   MAY THE SOURCE BE WITH YOU
                                              LINUX

Re: ld problem

[amodra]

On Mon, Apr 23, 2001 at 10:26:23AM -0400, Robert Schweikert wrote:
> 
> Now if I use the same link command with the exception of replacing the
> link script name with a -u uexternaldb_ everything works as expected.
> What am I messing up here?

Possibly just the location of your `EXTERN' statements.  Put them near
the start of your linker script.

Alan Modra

ld problem

[Robert Schweikert]

Hi,

I am trying to generate a shared library by linking an object file (.o)
an archive (.a) and some other shared library (.so) on a linux system.
When linking the object code (.o) file I want to force some symbols to
be undefined, such that they are linked from the archive, where they are
defined. If I use the -u option this is working. However, since I have a
number of symbols and don't want to list them all on the command line I
wanted to use a linker script, and that is not working for me at all.
The script basically has a bunch of EXTERN definitions in it, and
according to the documentation this is the same as -u on the command
line. Here is a snippet.

EXTERN(ucorr_);
EXTERN(uel_);
EXTERN(uexpan_);
EXTERN(uexternaldb_);
EXTERN(ufield_);
EXTERN(ufluid_);

There are no complaints during linking, but when I try to load the
library created with this linker script I get the following error.

error while loading shared libraries: undefined symbol: uexternaldb_

Now if I use the same link command with the exception of replacing the
link script name with a -u uexternaldb_ everything works as expected.
What am I messing up here?

The info pages state the following:

`EXTERN(SYMBOL SYMBOL ...)'
     Force SYMBOL to be entered in the output file as an undefined
     symbol.  Doing this may, for example, trigger linking of additional

     modules from standard libraries.  You may list several SYMBOLs for
     each `EXTERN', and you may use `EXTERN' multiple times.  This
     command has the same effect as the `-u' command-line option.

Any help is much appreciated. This is on a SuSE 7.1 and RedHat 6.2
system

SuSE:
ld -v
GNU ld version 2.10.91 (with BFD 2.10.0.33)

RedHat:
ld -v
GNU ld version 2.9.5 (with BFD 2.9.5.0.22)


Thanks,
Robert

--
Robert Schweikert                   MAY THE SOURCE BE WITH YOU
                                              LINUX

ld problem

[Aner Fust]

hi,
   
 i get this message when compling a foo.cpp file: 
 /usr/bin/ld: warning: libc.so.6, needed by /usr/libc/libstdc++.so, may 
 conflict with libc.so.5 
 
In addition the program (i think this it is related, since it is a simple  hello world prog) when run reoports a segmentation fault(copre dump) message. 
(ps my there are no problems with a foo.c files)
thanks
aner