嵌入式start.S启动文件详细介绍

MikelSun

于 2025-01-07 12:40:35 发布

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本文链接：https://blog.youkuaiyun.com/m0_59091453/article/details/144982886

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先来看一个具体的嵌入式工程的start.S文件：

#include "hpm_csr_regs.h"

    .section .start, "ax"

    .global _start
    .type _start,@function

_start:
    /* Initialize global pointer */
    .option push
    .option norelax

    la gp, __global_pointer$
    la tp, __thread_pointer$
    .option pop

    /* reset mstatus to 0*/
    csrrw x0, mstatus, x0

#ifdef __riscv_flen
    /* Enable FPU */
    li t0, CSR_MSTATUS_FS_MASK
    csrrs t0, mstatus, t0

    /* Initialize FCSR */
    fscsr zero
#endif

    /* Enable LMM1 clock */
    la t0, 0xF4000800
    lw t1, 0(t0)
    ori t1, t1, 0x80
    sw t1, 0(t0)

#ifdef INIT_EXT_RAM_FOR_DATA
    la t0, _stack_safe
    mv sp, t0
    call _init_ext_ram
#endif

    /* Initialize stack pointer */
    la t0, _stack
    mv sp, t0

    /*
     * Initialize LMA/VMA sections.
     * Relocation for any sections that need to be copied from LMA to VMA.
     */
    call c_startup

#if defined(__SES_RISCV)
    /* Initialize the hea