凡在系统codeS从X86-64大会来吗？ [英] Where are the system codes coming from in x86-64 Assembly?

问题描述

我期待通过装配的一些演示（在Mac上使用NASM，我是新来组装），看到这样的事情：

I am looking through some demos of assembly (using NASM on a Mac, I am new to assembly) and seeing things like this:

; read a byte from stdin
mov eax, 3     ; 3 is recognized by the system as meaning "read"
mov ebx, 0     ; read from standard input
mov ecx, variable    ; address to pass to
mov edx, 1     ; input length (one byte)
int 0x80             ; call the kernel

我开始明白， EAX ， EBX 等都是通用寄存器，这是在哪里您存储常用的东西。还有更多的学习有，但我得到了它的要点。

I am beginning to understand that eax, ebx, etc. are "general registers", which is where you store common things. Still have more to learn there but I get the gist of it.

不过，我很困惑，其中类似 3 值（被系统识别为意思是读的）和 0 （从标准输入读取的）的来源。你怎么知道 0 表示标准输入？有没有这样的整数值的清单，或者一些书籍或标准的参考？

But I am confused as to where the values like 3 (recognized by the system as meaning "read") and 0 (read from standard input) are coming from. How do you know that 0 means "standard input"? Is there a list of such integer values, or some book or standard reference?

推荐答案

您正在混为一谈系统调用号与系统调用的参数。

You're conflating system call numbers with the system call arguments.

系统呼叫号码（例如，3 =读）是特定于操作系统（当然，内核专用），有时版本特定的。例如，看到在x86 用于Linux的系统调用号在这里，并在x86_64 这里。如何参数传递，系统调用是如何调用的，哪些系统调用数字的含义都是建筑 - 和具体的内核。

The system call numbers (e.g. "3 = read") are OS-specific (well, kernel-specific), and sometimes version-specific. For example, see the system call numbers for Linux on x86 here and on x86_64 here. How the arguments are passed, how the system call is invoked, and what the system call numbers mean are all architecture- and kernel-specific.

有关，另一方面标准输入是一个UNIX规范值， STDIN_FILENO 。

The number "0" for "standard input" on the other hand is a UNIX standardized value, STDIN_FILENO.

这篇关于凡在系统codeS从X86-64大会来吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！