__init in linux kernel code

最新推荐文章于 2025-04-07 08:49:43 发布

转载最新推荐文章于 2025-04-07 08:49:43 发布 · 234 阅读

文章标签：

#linux #linker #initialization #compiler #macros #file

本文解释了Linux内核代码中__init宏的作用及其工作原理。__init用于标记那些仅在系统启动时运行一次的初始化代码，并允许内核在初始化完成后释放这部分内存以供重复使用。文章还提到了为实现这一特性所需使用的特殊链接脚本。

what is __init in linux kernel code.

These are only macros to locate some parts of the linux code into special
areas in the final executing binary.
__init for example (or better the __attribute__ ((__section__
(".init.text"))) this macro expands to) instructs the compiler to mark this
function in a special way. At the end the linker collects all functions
with this mark at the end (or begin) of the binary file. When the kernel
starts, this code runs only once (initialization). After it runs, the
kernel can free this memory to reuse it and you will see the kernel
message:
Freeing unused kernel memory: 108k freed

To use this feature, you need a special linker script file, that tells the
linker where to locate all the marked functions.
(see arch/arm/kernel/vmlinux.lds.S)