出现问题：
$nasm -f elf hello.asm -o hello.o
$ld -s hello.o -o hello
ld: i386 architecture of input file `hello.o' is incompatible with i386:x86-64 output
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尝试：
$ ld -m32 -s hello.o -o hello
ld: unrecognised emulation mode: 32
Supported emulations: elf_x86_64 elf32_x86_64 elf_i386 i386linux elf_l1om elf_k1om i386pep i386pe
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解决：
$nasm -f elf hello.asm -o hello.o
$ld -m elf_i386 -s hello.o -o hello
$./hello
Hello, world!