rtems start.s中一些汇编字符的学习

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#rtems #start.s

本文深入探讨了rtems操作系统中start.s汇编文件的几个关键部分，包括.data、.bss和.text段。在_start标签下，可以看到初始化数据、未初始化数据的处理，以及汇编指令如mov r1,#1等用于设置寄存器值的操作。" 106244919,9042557,Java实现QQ一键登录教程,"['java', 'spring', 'spring boot', 'QQ互联', '登录']

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在看start.s时有些汇编不理解，

1:  .arm是什么意思？
2：.globl _start 的作用？
3：.section ".bsp_start_text", "ax"  的意思？

通过下面的解释就一目了然了。

一、汇编一般使用的场合：
（1）、汇编语言在ARM中一般用在启动代码中，比如Bootloader 初始化时对 CPU 和 协处理器 等进行初始化, 此时没有建立起 C 语言运行环境, 这个时候使用汇编语言执行初始化操作;
（2）、汇编效率比较高, 在Linux 内核中对效率有特殊要求的地方也会使用汇编语言来编写. 

二、ARM汇编的分类：汇编语言可以分为ARM标准汇编语言和GNU汇编语言两种；
他们使用的地方是不同的，一般来说ARM标准汇编语言适用于ARM公司的汇编器, 适合在 Windows 平台使用, 如ADS
而GNU汇编语言适用于 Linux 平台交叉编译工具链的汇编器。
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