Converting a JAR into a gcj-statically-linked SO

Fri Jan 11 21:05:00 GMT 2008

On 2008年1月11日, Matthijs van de Water wrote:
> On Jan 10, 2008 9:14 AM, Marco Trudel <marco@mtsystems.ch> wrote:
>> Matthijs van de Water wrote:
>>> The only down-side is that the resulting shared library is 24MB big
>>> even after stripping and optimizing. I was expecting a lot less, is
>>> there any chance the compiler is linking in stuff that is not actually
>>> needed?
>>>> Yes. Use "-Wl,-Map,/tmp/linkmap.txt" to get the link map.
>> For instance, you will always end up with the whole AWT (maybe even
>> Swing) because the SecurityManager imports an AWT class. There are a lot
>> of other such never needed imports.
>> You can stub out certain objects. JNC (http://jnc.mtsystems.ch/) does
>> this for instance for AWT/Swing or JCE. I explained a couple of times on
>> the list how I do it. So, searching for my name in the archives should
>> bring up something useful.
>> Actually, I even created a project named GcjStubber about half a year
>> ago that takes a statically compiled GCJ and creates a stub for all
>> objects in libgcj.a. For compilation of applications, you can then add
>> stubs for objects you don't need and therefore exclude the original
>> objects. But so far, I didn't really finish it (it's about 90% done).
>> But you're still invited to check it out in case you are interested:
>> http://sourceforge.net/svn/?group_id=169793
>> This is very useful. I'm currently investigating this approach.
> I also like the micro-libgcj approach; as it turns out I'm only
> missing a hand full of methods in that, which should be not too hard
> to put back in.

Hi Matthijs. Please be aware that micro-libgcj is based on GCC 4.1.1, 
which means there is no support for Java 1.5 features such as generics, 
and it has not been tested on ARM, nor does it have the recent ARM 
patches in the GCC trunk.
I've spent some time trying to update micro-libgcj to work with a snapshot 
of the GCC trunk, but it was more work than I expected. Moreover, I 
decided that I'm not prepared to maintain such a large and invasive patch 
indefinitely. So micro-libgcj is dormant for now.
In your situation, I recommend using Marco's technique instead.
> Thanks for the help Andrew, David and Marco! I'm sure I'll be back
> with questions as soon as I need to get this ported to ARM ;)
>> Regards,
>> Matthijs