How to use "make" to use 64 bit libs because of ELFCLASS64 error - c++

Question

How can I use configure and make tools to specify to use 64 bit libraries? I thought it was automatic, but I get wrong ELF Class.
I'm trying to compile Xdebug for Ubuntu 64 for use with LAMPP (XAMPP for Linux).
./lampp start
Failed loading /opt/lampp/lib/php/extensions/xdebug.so: /opt/lampp/lib/php/extensions/xdebug.so: wrong ELF class: ELFCLASS64
The ./configure looks OK to me, and the make works without errors, I've copied the configure in case its relevant:
/xdebug-2.0.3$ ./configure
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for a sed that does not truncate output... /bin/sed
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking whether gcc and cc understand -c and -o together... yes
checking for system library directory... lib
checking if compiler supports -R... no
checking if compiler supports -Wl,-rpath,... yes
checking build system type... x86_64-unknown-linux-gnu
checking host system type... x86_64-unknown-linux-gnu
checking target system type... x86_64-unknown-linux-gnu
checking for PHP prefix... /usr
checking for PHP includes... -I/usr/include/php5 -I/usr/include/php5/main -I/usr/include/php5/TSRM -I/usr/include/php5/Zend -I/usr/include/php5/ext -I/usr/include/php5/ext/date/lib
checking for PHP extension directory... /usr/lib/php5/20060613
checking for PHP installed headers prefix... /usr/include/php5
checking for re2c... no
configure: WARNING: You will need re2c 0.12.0 or later if you want to regenerate PHP parsers.
checking for gawk... no
checking for nawk... nawk
checking if nawk is broken... no
checking whether to enable eXtended debugging support... yes, shared
checking for gettimeofday... yes
checking for cos in -lm... yes
checking for a sed that does not truncate output... (cached) /bin/sed
checking for fgrep... /bin/grep -F
checking for ld used by gcc... /usr/bin/ld
checking if the linker (/usr/bin/ld) is GNU ld... yes
checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B
checking the name lister (/usr/bin/nm -B) interface... BSD nm
checking whether ln -s works... yes
checking the maximum length of command line arguments... 1572864
checking whether the shell understands some XSI constructs... yes
checking whether the shell understands "+="... yes
checking for /usr/bin/ld option to reload object files... -r
checking for objdump... objdump
checking how to recognize dependent libraries... pass_all
checking for ar... ar
checking for strip... strip
checking for ranlib... ranlib
checking command to parse /usr/bin/nm -B output from gcc object... ok
checking how to run the C preprocessor... gcc -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for dlfcn.h... yes
checking for objdir... .libs
checking if gcc supports -fno-rtti -fno-exceptions... no
checking for gcc option to produce PIC... -fPIC -DPIC
checking if gcc PIC flag -fPIC -DPIC works... yes
checking if gcc static flag -static works... yes
checking if gcc supports -c -o file.o... yes
checking if gcc supports -c -o file.o... (cached) yes
checking whether the gcc linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking whether -lc should be explicitly linked in... no
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
configure: creating ./config.status
config.status: creating config.h
config.status: config.h is unchanged
config.status: executing libtool commands

Answer 1

I'm not sure of the error, but why are you compiling xdebug? Its available in the repositories of Ubuntu as php5-xdebug (sudo apt-get install php5-xdebug). Though you don't mention your distribution, perhaps its under a similar name?
But to answer your question, the error message looks like xdebug is 64 bit, but that's a problem (is something lampp executes a 32 bit binary?)

Answer 2

Won't:
LD_LIBRARY_PATH=/lib64:$LD_LIBRARY_PATH ./lampp start
work? I don't use Ubuntu, so your path might vary. One thing to do is
ldd ./lampp
to see what the default executable points to.

Answer 3

xdebug was getting compiled in 32 bit. Compile it using:
CXXFLAGS="-m64" CFLAGS="-m64" LDFLAGS="-m64" ./configure --enable-xdebug
worked for me on SPARC Solaris 10.

Answer 4

Try pointing to the 32 bit libs, LD_LIBRARY_PATH=/lib32:LD_LIBRARY_PATH.
If that doesn't work, try the 64 bit libs, LD_LIBRARY_PATH=/lib64:LD_LIBRARY_PATH.
Complete command:
sudo ./configure --enable-xdebug --with-php-config=/opt/lampp/bin/php-config LD_LIBRARY_PATH=/lib32:LD_LIBRARY_PATH

Answer 5

Maybe the runtime linker's library path is wrong. Does the directory /opt/lampp/lib64 exist? Is lampp a shell script? If so, to what value (and whether) does it set the LD_LIBRARY_PATH variable?