gcc -O3 -c crc32.c 
ocamlopt crc32.o unix.cmxa crc32.ml testcrc.ml -o crc


crc32.o(.data+0x0): In function `camlCrc32__data_begin':
: multiple definition of `camlCrc32__data_begin'
crc32.o(.data+0x0): first defined here
crc32.o(.text+0x0): In function `camlCrc32__read_92':
: multiple definition of `camlCrc32__code_begin'
crc32.o(.text+0x0): first defined here
crc32.o(.data+0x4): In function `camlCrc32':
: multiple definition of `camlCrc32'
crc32.o(.data+0x4): first defined here
crc32.o(.text+0x460): In function `camlCrc32__crc32unix_107':
: multiple definition of `camlCrc32__crc32unix_107'
crc32.o(.text+0x460): first defined here
crc32.o(.text+0x3b0): In function `camlCrc32__crc32stream_101':
: multiple definition of `camlCrc32__crc32stream_101'
crc32.o(.text+0x3b0): first defined here
crc32.o(.text+0x360): In function `camlCrc32__crc32_90':
: multiple definition of `camlCrc32__crc32_90'
crc32.o(.text+0x360): first defined here
crc32.o(.text+0x2d0): In function `camlCrc32__calc_78':
: multiple definition of `camlCrc32__calc_78'
crc32.o(.text+0x2d0): first defined here
crc32.o(.text+0x280): In function `camlCrc32__index_76':
: multiple definition of `camlCrc32__index_76'
crc32.o(.text+0x280): first defined here
crc32.o(.text+0x240): In function `camlCrc32__$7e$7e_73':
: multiple definition of `camlCrc32__$7e$7e_73'
crc32.o(.text+0x240): first defined here
crc32.o(.text+0x200): In function `camlCrc32__$26_70':
: multiple definition of `camlCrc32__$26_70'
crc32.o(.text+0x200): first defined here
crc32.o(.text+0x1c0): In function `camlCrc32__$5e$5e_67':
: multiple definition of `camlCrc32__$5e$5e_67'
crc32.o(.text+0x1c0): first defined here
crc32.o(.text+0x180): In function `camlCrc32__$3c$3c_64':
: multiple definition of `camlCrc32__$3c$3c_64'
crc32.o(.text+0x180): first defined here
crc32.o(.text+0x140): In function `camlCrc32__$3e$3e_61':
: multiple definition of `camlCrc32__$3e$3e_61'
crc32.o(.text+0x140): first defined here
crc32.o(.text+0x130): In function `camlCrc32__fun_132':
: multiple definition of `camlCrc32__fun_132'
crc32.o(.text+0x130): first defined here
crc32.o(.text+0x0): In function `camlCrc32__read_92':
: multiple definition of `camlCrc32__read_92'
crc32.o(.text+0x0): first defined here
crc32.o(.text+0x100): In function `camlCrc32__calc_105':
: multiple definition of `camlCrc32__calc_105'
crc32.o(.text+0x100): first defined here
crc32.o(.text+0x5c0): In function `camlCrc32__entry':
: multiple definition of `camlCrc32__entry'
crc32.o(.text+0x5c0): first defined here
crc32.o(.text+0x684): In function `camlCrc32__code_end':
: multiple definition of `camlCrc32__code_end'
crc32.o(.text+0x684): first defined here
crc32.o(.data+0x1530): In function `camlCrc32__data_end':
: multiple definition of `camlCrc32__data_end'
crc32.o(.data+0x1530): first defined here
crc32.o(.data+0x1534): In function `camlCrc32__frametable':
: multiple definition of `camlCrc32__frametable'
crc32.o(.data+0x1534): first defined here
testcrc.o(.text+0x4b0): In function `camlTestcrc__fun_164':
: undefined reference to `caml_crc32'
collect2:  ld    1
Error during linking