Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Thu, 27 Sep 2012 15:27:12 +0000

Hi Janet,

Thanks, that worked!

This is very useful when building shareable libraries that we distribute to users without EPICS build systems.  The library is then completely self-contained and they don't need to install libCom.so, libezca.so, etc. somewhere and make the system find them at run-time with LD_LIBRARY_PATH or some other mechanism.

Mark

-----Original Message-----
From: Janet Anderson [mailto:[email protected]] 
Sent: Thursday, September 27, 2012 10:08 AM
To: Andrew Johnson
Cc: [email protected]; Mark Rivers
Subject: Re: Building a self-contained shareable library

You could try adding the following lines to the Makefile that creates the 
shareable library.

SHARED_LIBRARIES = YES
STATIC_BUILD = YES
<libraryname>_LDFLAGS = $(STATIC_LDFLAGS)

On 09/26/2012 05:56 PM, Andrew Johnson wrote:
> 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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System