OSX中gcc使用的文件格式是什麼？

Question

我正在嘗試使用NASM學習程序集，Paul Carter博士的pcasm-book.pdf - http://www.drpaulcarter.com/pcasm/ - 在我的Mac OS X Snow Leopard上。

我想以前編譯的C樣品鏈接到ASM樣本：

gcc first.o driver.c asm_io.o -o first 

但它返回它：

driver.c:3: warning: ‘cdecl’ attribute ignored 
ld: warning: in first.o, **file is not of required architecture** 
ld: warning: in asm_io.o, file is not of required architecture 
Undefined symbols: 
    "_asm_main", referenced from: 
     _main in ccjLqYJn.o 
ld: symbol(s) not found 

我使用的Mach-O的格式編寫彙編樣本，我沒有錯誤：

nasm -f macho **first.asm** 
nasm -f macho asm_io.asm 

如果我嘗試在driver.c中只使用gcc -c，使用ld鏈接所有目標文件，l d似乎沒有鏈接driver.o格式。

ld -o first asm_io.o first.o driver.o 

它返回：

ld: warning: in driver.o, file is not of required architecture 
Undefined symbols: 
    "_putchar", referenced from: 
     print_char in asm_io.o 
     print_nl in asm_io.o 
    "_printf", referenced from: 
     print_int in asm_io.o 
     print_string in asm_io.o 
     push_of in asm_io.o 
     sub_dump_stack in asm_io.o 
     stack_line_loop in asm_io.o 
     sub_dump_mem in asm_io.o 
     mem_outer_loop in asm_io.o 
     mem_hex_loop in asm_io.o 
     sub_dump_math in asm_io.o 
     tag_loop in asm_io.o 
     print_real in asm_io.o 
     invalid_st in asm_io.o 
    "_scanf", referenced from: 
     read_int in asm_io.o 
    "_getchar", referenced from: 
     read_char in asm_io.o 
ld: symbol(s) not found for inferred architecture i386 

什麼問題？在OS X上使用gcc和NASM的正確格式是什麼？

謝謝。 Daniel Koch

Answer 1

「文件不是必需的體系結構」表示您嘗試鏈接不同體系結構的目標文件：可能是x86_64和i386。由於看起來您的nasm輸出是i386，請嘗試使用-arch i386和gcc。您還可以使用file來顯示給定對象文件或庫的體系結構。

% touch foo.c ; gcc -c foo.c 
% file foo.o 
foo.o: Mach-O 64-bit object x86_64 
% gcc -c -arch i386 foo.c 
% file foo.o    
foo.o: Mach-O object i386