why cant link 64bit static libgcc on ubuntu

Question

I have problem link libgcc into a static linked .so

it only happens when linking 64bit module with -m64

Ubuntu 64bit 12.10 gcc 4.7

also failed on Ubuntu 64bit 12.04 gcc 4.6

32bit no problem

$gcc -fPIC -c -o hello.o hello.c -m32
$gcc -shared -m32 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic  -lc
$ ldd libhello.so 
    statically linked

64bit failed

$ make
gcc -fPIC -c -o hello.o hello.c
gcc -shared -m64 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic  -lc
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libc.a(iofclose.o): relocation R_X86_64_32 against `__gcc_personality_v0' can not be used when making a shared object; recompile with -fPIC
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libc.a: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
make: *** [libhello.so] Error 1

hello.c

#include <stdio.h>

int f(){

FILE *out = fopen("/tmp/x.log", "wb");
fclose(out);

return 1;
}

Makefile

all: libhello.so

libhello.so: hello.o
    gcc -shared -m64 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic  -lc

hello.o: hello.c
    gcc -fPIC -c -o hello.o hello.c

clean: 
    rm -f hello.o libhello.so

Answer 1

The answer is basically "you can't do that." You're trying to link non-PIC code into a shared library, which is simply impossible on the x86_64 (amd64) architecture. You would need a static but PIC version of libgcc, and I suspect that would be only the start of your problems.

One of the reasons why libgcc is normally shared is that a given running executable has to have one and only one copy of some of the key data structures that libgcc maintains. Static linking makes sense for a final executable, since that one and only one copy will be the one statically linked into the executable, but the whole point of a dynamic object is to be loaded into another executable (which in turn will have its own copy of libgcc, either shared or static).