链接问题：i386：x86-64输入文件架构* .o与i386输出不兼容

Question

I got a problem in linking when I moved my osdev to linux where it worked previously on gcc 3.5.* and binutils 2.18 (compiled to output x86_64-elf) running under cygwin.

Here are the infos:

gcc -v

Using built-in specs.
Target: i686-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.4-14ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu --target=i686-linux-gnu
Thread model: posix
gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5) 

ld -v

GNU ld (GNU Binutils for Ubuntu) 2.20.51-system.20100908

part of ld -help

....

ld: supported targets: elf32-i386 a.out-i386-linux pei-i386 elf32-little elf32-big elf64-x86-64 pei-x86-64 elf64-l1om elf64-little elf64-big plugin srec symbolsrec verilog tekhex binary ihex trad-core

....

The code:

main.c

\nvoid main(){ 
 /**some code here**/ 
 } 

start.asm

\n[bits 64] 
 global start 
 extern main 
 start: 
 call main 

link.ld

 OUTPUT_FORMAT(elf64-x86-64); 
 offset = 0x1000000; 
 ENTRY(start); 
 SECTIONS{ 
 . = offset; 
 .text : AT(ADDR(.text) - offset){ 
 _code = .; 
 *(.text) 
 (.rodata ) 
 . = ALIGN(4096);} 
 .data : AT(ADDR(.data) - offset){ 
 _data = .; 
 *(.data) 
 . = ALIGN(4096);} 
 .bss : AT(ADDR(.bss) - offset){ 
 _bss = .; 
 *(.bss) 
 *(COMMON) 
 . = ALIGN(4096);} 
 _end = .; 
 /DISCARD/ : 
 {*(.comment)} 
 } 

build.sh

 nasm -f elf64 -o start.o start.asm 
 echo . 
 echo . 
 echo . 
 gcc -m64 -ffreestanding -nostdlib -mno-red-zone -mno-mmx -mno-sse -mno-sse2 -mno-sse3 -mno-3dnow -c -o main.o main.c 
 echo . 
 echo . 
 echo . 
 ld -nostdlib -nodefaultlibs -T link.ld -o out.elf start.o main.o 
 

terminal output

 . 
 . 
 . 
 . 
 . 
 . 
 ld: i386:x86-64 architecture of input file 'start.o' is incompatible with i386 output 
 ld: i386:x86-64 architecture of input file 'main.o' is incompatible with i386 output 

I don't understand why it displays 'incompatible with i386 output' when there's OUTPUT_FORMAT(elf64-x86-64); in my linker script specifying the targeted output..

Answer 1

Try this:

LDEMULATION="elf_x86_64"
ld -nostdlib -nodefaultlibs -T link.ld -o out.elf start.o main.o