Hi all I need to implemente a Java class which uses JNI to control a fiscal printer in XUbuntu 8.10 with sun-java6-jdk installed. The structure is the following: EpsonDriver.java loads libEpson.so libEpson is linked dynamically with EpsonFiscalProtocol.so ( provided by Epson, no source available ) and pthread I use javah to generate the header file, and the code compiles. Then I put the libEpson.so in $JAVA_HOME/jre/lib/i386, and EpsonDriver.java uses an static initializar System.loadLibrary("libEpson") That part works, however, when I try to use any of the methods I get an unsatisfiedLinkError exception. Some time ago, a coworker did a version that works, and using objdump -Dslx I got the following: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x0000ccc4 memsz 0x0000ccc4 flags r-x LOAD off 0x0000d000 vaddr 0x0000d000 paddr 0x0000d000 align 2**12 filesz 0x00000250 memsz 0x00044a5c flags rw- DYNAMIC off 0x0000d014 vaddr 0x0000d014 paddr 0x0000d014 align 2**2 filesz 0x000000f0 memsz 0x000000f0 flags rw- NOTE off 0x000000d4 vaddr 0x000000d4 paddr 0x000000d4 align 2**2 filesz 0x00000024 memsz 0x00000024 flags r-- STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2 filesz 0x00000000 memsz 0x00000000 flags rw- Dynamic Section: NEEDED EpsonFiscalProtocol.so NEEDED libpthread.so.0 NEEDED libstdc++.so.6 NEEDED libm.so.6 NEEDED libc.so.6 SONAME libcom_tichile_jpos_EpsonSerialDriver.so INIT 0x00007254 FINI 0x0000ba08 GNU_HASH 0x000000f8 STRTAB 0x00001f50 SYMTAB 0x00000ae0 STRSZ 0x00002384 SYMENT 0x00000010 PLTGOT 0x0000d108 PLTRELSZ 0x00000008 PLTREL 0x00000011 JMPREL 0x0000724c REL 0x000045c4 RELSZ 0x00002c88 RELENT 0x00000008 TEXTREL 0x00000000 VERNEED 0x00004564 VERNEEDNUM 0x00000002 VERSYM 0x000042d4 RELCOUNT 0x000000ac Version References: required from libstdc++.so.6: 0x056bafd3 0x00 05 CXXABI_1.3 0x08922974 0x00 04 GLIBCXX_3.4 required from libc.so.6: 0x0b792650 0x00 03 GCC_3.0 0x0d696910 0x00 02 GLIBC_2.0 In the recently compiled file I get: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x00005300 memsz 0x00005300 flags r-x LOAD off 0x00005300 vaddr 0x00006300 paddr 0x00006300 align 2**12 filesz 0x00000274 memsz 0x00010314 flags rw- DYNAMIC off 0x00005314 vaddr 0x00006314 paddr 0x00006314 align 2**2 filesz 0x000000e0 memsz 0x000000e0 flags rw- EH_FRAME off 0x00004a00 vaddr 0x00004a00 paddr 0x00004a00 align 2**2 filesz 0x00000154 memsz 0x00000154 flags r-- Dynamic Section: NEEDED libstdc++.so.5 NEEDED libm.so.6 NEEDED libgcc_s.so.1 NEEDED libc.so.6 SONAME EpsonFiscalProtocol.so INIT 0x00001cb4 FINI 0x00004994 HASH 0x000000b4 STRTAB 0x00000da4 SYMTAB 0x000004f4 STRSZ 0x00000acf SYMENT 0x00000010 PLTGOT 0x0000640c PLTRELSZ 0x00000270 PLTREL 0x00000011 JMPREL 0x00001a44 REL 0x000019dc RELSZ 0x00000068 RELENT 0x00000008 VERNEED 0x0000198c VERNEEDNUM 0x00000002 VERSYM 0x00001874 RELCOUNT 0x00000004 Version References: required from libstdc++.so.5: 0x056bafd2 0x00 04 CXXABI_1.2 required from libc.so.6: 0x09691f73 0x00 03 GLIBC_2.1.3 0x0d696910 0x00 02 GLIBC_2.0 So I suspect the main diference is the GCC_3.0 symbol I compile libcom_tichile_EpsonSerialDriver.so with the following command ( from memory as I not at work right now ) g++ -Wl,-soname=.... -shared -I/*jni libraries*/ -o libcom_tichile_jpos_EpsonSerialDriver -lEpsonFiscalProtocol -lpthread Is there any way to tell g++ to use that symbol version? Or any idea in how to make it work? EDIT: I have another non-working version with the followin dump: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x0000bf68 memsz 0x0000bf68 flags r-x LOAD off 0x0000cc0c vaddr 0x0000cc0c paddr 0x0000cc0c align 2**12 filesz 0x000005e8 memsz 0x00044df0 flags rw- DYNAMIC off 0x0000cc20 vaddr 0x0000cc20 paddr 0x0000cc20 align 2**2 filesz 0x000000f8 memsz 0x000000f8 flags rw- EH_FRAME off 0x0000b310 vaddr 0x0000b310 paddr 0x0000b310 align 2**2 filesz 0x000002bc memsz 0x000002bc flags r-- STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2 filesz 0x00000000 memsz 0x00000000 flags rw- RELRO off 0x0000cc0c vaddr 0x0000cc0c paddr 0x0000cc0c align 2**0 filesz 0x000003f4 memsz 0x000003f4 flags r-- Dynamic Section: NEEDED EpsonFiscalProtocol.so NEEDED libpthread.so.0 NEEDED libstdc++.so.6 NEEDED libm.so.6 NEEDED libgcc_s.so.1 NEEDED libc.so.6 SONAME libcom_tichile_jpos_EpsonSerialDriver.so INIT 0x000055d8 FINI 0x0000a968 HASH 0x000000f4 GNU_HASH 0x00000a30 STRTAB 0x00002870 SYMTAB 0x00001410 STRSZ 0x00002339 SYMENT 0x00000010 PLTGOT 0x0000cff4 PLTRELSZ 0x00000168 PLTREL 0x00000011 JMPREL 0x00005470 REL 0x00004ea8 RELSZ 0x000005c8 RELENT 0x00000008 VERNEED 0x00004e38 VERNEEDNUM 0x00000002 VERSYM 0x00004baa RELCOUNT 0x00000001 Version References: required from libstdc++.so.6: 0x056bafd3 0x00 05 CXXABI_1.3 0x08922974 0x00 03 GLIBCXX_3.4 required from libc.so.6: 0x09691f73 0x00 06 GLIBC_2.1.3 0x0d696914 0x00 04 GLIBC_2.4 0x0d696910 0x00 02 GLIBC_2.0 Now I think the main difference is in the GCC_3.0 symbol/ABI EDIT: Luckily, a coworker found a way to talk to the printer using Java