如何使用nasm编译x86汇编代码？我收到一个错误

Question

我一直在尝试在Linux上学习x86 Assembly，这是我的代码：

.386
.model flat
.code
start PROC
    mov eax, 100
    add eax, 200

    ret
start endp
end start

每当我尝试使用nasm进行编译时，就像这样：

nasm -f elf32 -o <filename>.o <filename>.asm
ld -m elf_i386 -o <filename> <filename>.o

我收到此错误：

simple.asm:1: warning: label alone on a line without a colon might be in error [-w+orphan-labels]
simple.asm:1: error: attempt to define a local label before any non-local labels
simple.asm:2: error: attempt to define a local label before any non-local labels
simple.asm:2: error: parser: instruction expected
simple.asm:3: warning: label alone on a line without a colon might be in error [-w+orphan-labels]
simple.asm:3: error: attempt to define a local label before any non-local labels
simple.asm:4: error: parser: instruction expected
simple.asm:9: error: symbol `start' redefined
simple.asm:9: error: parser: instruction expected
simple.asm:10: error: parser: instruction expected

为什么会出现该错误？是编译器还是代码？以及如何解决？