linux audio software using gcj&swt!
Thu Oct 23 11:33:00 GMT 2003
Norbert Frese writes:
> > Static linking with Java is tricky. Certain resources may be missing
> > because they are only loaded dynamically (ie Class.forName), and the
> > linker can't see that to include them. One workaround is to add static
> > links to the missing classes in your code ie:
> > static class foo = gnu.java.localeCalendar.class;
> i have added the lines
> static Class foo = gnu.java.locale.Calendar.class;
> static Class foo2 = gnu.java.locale.LocaleInformation.class;
> and the exceptions are gone. but there seems to be a problem with swt
> now. the appliction starts up - then hangs (cpu 99%) for a while and
> drops core (segmentation fault). (i think it hangs inside "new
I've seen that. I think it happens when trying to load a shared
library from a static executable. Run your app in gdb; you might see
#0 0x00000000 in ?? ()
#1 0x40caf3a6 in ?? ()
#2 0x40cb4761 in ?? ()
#3 0x40ca9b99 in ?? ()
#4 0x081908da in _dl_init ()
#5 0x08179264 in dl_open_worker ()
#6 0x081785d3 in _dl_catch_error ()
#7 0x08178e3f in _dl_open ()
#8 0x08153208 in dlopen_doit ()
#9 0x081785d3 in _dl_catch_error ()
#10 0x08153490 in _dlerror_run ()
#11 0x081531d5 in dlopen ()
#12 0x0811ab03 in GC_dlopen (path=0x0, mode=0) at /local/aph/gcc/gcc/boehm-gc/gc_dlopen.c:81
#13 0x080bdbbb in sys_dl_open (loader_data=0x0, filename=0x0)
#14 0x080bb716 in tryall_dlopen (handle=0xbfffe1b8, filename=0x83730e0 "lib-foo.so")
#15 0x080bc768 in lt_dlopen (filename=0x83730e0 "lib-foo.so")
#16 0x080bda60 in lt_dlopenext (filename=0xbfffe210 "lib-foo")
#17 0x08072160 in java::lang::Runtime::loadLibraryInternal(java::lang::String*) (this=0x0,
lib=0x81c1aac) at /local/aph/gcc/gcc/libjava/java/lang/natRuntime.cc:272
Maybe we can't load a library from a statically linked exectuable
without crashing. Let's try something simple:
int main ()
dlopen ("lib-foo.so", RTLD_NOW);
char *s = dlerror();
puts (s ? s : "");
$ gcc z.c -ldl -static -g
$ gdb ./a.out
GNU gdb 5.2.1
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GDB is free software, covered by the GNU General Public License, and you are
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This GDB was configured as "i686-pc-linux-gnu"...
Starting program: /cuddles/aph/home/a.out
Program received signal SIGSEGV, Segmentation fault.
0x00000000 in ?? ()
#0 0x00000000 in ?? ()
#1 0x409163a6 in ?? ()
#2 0x4091b761 in ?? ()
#3 0x40910b99 in ?? ()
#4 0x0807b6ba in _dl_init ()
#5 0x0805b920 in dl_open_worker ()
#6 0x0805ac8f in _dl_catch_error ()
#7 0x0805b4fb in _dl_open ()
#8 0x0804829c in dlopen_doit ()
#9 0x0805ac8f in _dl_catch_error ()
#10 0x080484a4 in _dlerror_run ()
#11 0x08048269 in dlopen ()
#12 0x08048214 in main () at z.c:5
#13 0x08048813 in __libc_start_main ()
Bingo. Same error.
If I try this same experiment with libc.so.6, instead of lib-foo.so
there is no problem. I think it's because the lib-foo.so I created
depends on libgcc_s.so.1 and libgcj.so.4, and there are static
versions of thses already linked to the executable.
So, we shouldn't attempt to load a shared library from a static gcj
executable. I don't think there's any way to make it work.
> i guess building a static binary (which includes libgcj) on linux is
> really a tricky task. i've seen that other people gave up on this (read
> the posts on this mailing list). :-(
Well, the question here is why libgcj is trying to load a library.
There must be a reason, probably because some dependency in Display is
trying to resolve something in a shared library.
Time to debug.
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