Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 26 Sep 2012 17:56:21 -0500

Hi Mark,

On 2012-09-26 Mark Rivers wrote:
> I would like to build an EPICS shareable library on Linux that is
> self-contained, i.e. it does not depend on any other shareable library. 
> For example, with IDL I would like libezcaIDL.so to not depend on
> libca.so, libCom.so, libezca.so, and libEzcaScan.so.
...
> But I am looking for a cleaner solution.  When EPICS is built with
> SHARED_LIBRARIES=YES it actually builds both .a and .so files for every
> library.  I would like a way to specify that ezcaIDL should be built as a
> .so file, but it should be linked with .a files for everything it depends
> on.
> 
> Is there a way to do this?

You can change the command that we use to link a shared library by modifying 
the variable LINK.shrlib in your Makefile.  The value for this variable is set 
in one or more of the Base/configure/os/CONFIG.* files according to your 
platform.  For GNU-based platforms we actually use g++ to do the linking 
because it has to do more than the ld program normally does when linking C++ 
code.

Your replacement linker command should use the the -Wl,-Bstatic command-line 
option (or any of its synonyms which I won't list here) immediately before any 
-l options naming libraries that you want to statically link against, then -
Wl,-Bdynamic (or its synonyms) before the -l options naming shared libraries.  
You'll probably want to run this manually to get the right combination.

The EPICS build system doesn't have a way to do this automatically, and I 
think it would be rather complicated to try to make it do so.  Note that the 
resulting Makefile rule probably won't be portable; the above options apply to 
the GNU linker, you may have to adjust them for other platforms you want to 
use.

HTH,

- Andrew
-- 
Never interrupt your enemy when he is making a mistake.
-- Napoleon Bonaparte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System