gcc中的ffreestanding选项是什么？ [英] What is ffreestanding option in gcc?

问题描述

在gcc中 ffreestanding 是什么？它用于什么？我遇到了以下问题：

What is ffreestanding in gcc ? What is it used for ? I came across the following :

gcc -ffreestanding -m32 -c kernel.c -o kernel.o

并不明白，它的意思是什么。

and do not understand, what does it mean exactly.

推荐答案

独立的环境是标准库可能不存在，程序启动不一定在main的环境。选项 -ffreestanding 指示编译器不是假设标准函数有其通常的定义。

A freestanding environment is one in which the standard library may not exist, and program startup may not necessarily be at "main". The option -ffreestanding directs the compiler to not assume that standard functions have their usual definition.

默认情况下，GCC将作为托管实现的编译器，将 __ STDC_HOSTED __ 定义为1，并假设当使用ISO C函数的名称时，语义在标准中定义。要使其成为独立式环境的合适独立实现，请使用选项 -ffreestanding 。然后它将 __ STDC_HOSTED __ 定义为0，而不是假设标准库中的函数名的含义。

By default, GCC will act as the compiler for a hosted implementation, defining __STDC_HOSTED__ as 1 and presuming that when the names of ISO C functions are used, they have the semantics defined in the standard. To make it act as a conforming freestanding implementation for a freestanding environment, use the option -ffreestanding. It will then define __STDC_HOSTED__ to 0, and not make assumptions about the meanings of function names from the standard library.

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