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- torshie@Orz:/tmp$ cat t.c
- int f() {
- int x = 35;
- int y = 20;
- return x + y;
- }
- torshie@Orz:/tmp$ cat main.c
- extern int f();
- int main() {
- printf("%d\n", f());
- }
- torshie@Orz:/tmp$ gcc t.c -m32 -c
- torshie@Orz:/tmp$ gcc main.c -m64 -c
- main.c: In function ‘main’:
- main.c:3: warning: incompatible implicit declaration of built-in function ‘printf’
- torshie@Orz:/tmp$ gcc main.o t.o
- /usr/bin/ld: i386 architecture of input file `t.o' is incompatible with i386:x86-64 output
- collect2: ld returned 1 exit status
- torshie@Orz:/tmp$ objcopy t.o -O elf64-x86-64
- torshie@Orz:/tmp$ gcc main.o t.o
- torshie@Orz:/tmp$ ./a.out
- Segmentation fault
- torshie@Orz:/tmp$ gcc t.c -O2 -c -m32
- torshie@Orz:/tmp$ objcopy -O elf64-x86-64 t.o
- torshie@Orz:/tmp$ gcc t.o main.o
- torshie@Orz:/tmp$ ./a.out
- 55
- torshie@Orz:/tmp$ uname -a
- Linux Orz 2.6.27-7-generic #1 SMP Tue Nov 4 19:33:06 UTC 2008 x86_64 GNU/Linux
- torshie@Orz:/tmp$ cat /proc/cpuinfo |grep 'model name'
- model name : Intel(R) Core(TM)2 Duo CPU E8200 @ 2.66GHz
- model name : Intel(R) Core(TM)2 Duo CPU E8200 @ 2.66GHz
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