linux - How do i start to learn asm (gas)? -



linux - How do i start to learn asm (gas)? -

i found "hello world" , wrote it. nano hello.s

this code

.data msg: .string "hello, world!\n" len = . - msg .text global _start _start: movl $len,%edx movl $msg,%ecx movl $1,%ebx movl $4,%eax int $0x80 movl $0,%ebx movl $1,%eax int $0x80

i've done as -o hello.o hello.s i've given error

hello.s:6: error: no such instruction: global _start delete global _start.

i've done

ld -s -o hello.o hello* error ld: hello: no such file: no such file or directory

where mistaking?

p/s debian, amd64.

try .globl _start or .global _start.

you may seek ununderscored start in case run problem entry point.

finally, if you're making 64-bit executable, need utilize different scheme phone call interface, not int 0x80 syscall. more on here.

linux assembly x86-64 gas

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