一、LiteOS-M 初始化内核

在LiteOS-M应用程序中，系统初始化如下：

/**
 * @brief This is the ohos entry, and you could call this in your main funciton after the
 *        necessary hardware has been initialized.
 */
void OHOS_Boot(void)
{
    UINT32 ret;

    ret = LOS_KernelInit(); //初始化内核
    if (ret == LOS_OK) {
        ...
        LOS_Start();        //启动内核任务调度
    }
    return;  // and should never come here
}

二、LOS_KernelInit代码分析

/*****************************************************************************
 Function    : LOS_KernelInit
 Description : System kernel initialization function, configure all system modules
 Input       : None
 Output      : None
 Return      : LOS_OK on success or error code on failure
 *****************************************************************************/
LITE_OS_SEC_TEXT_INIT UINT32 LOS_KernelInit(VOID)
{
    UINT32 ret;
    PRINTK("entering kernel init...\n");

#if (LOSCFG_BACKTRACE_TYPE != 0)                        //LOSCFG_XXX 宏定义为make menuconfig生成的宏
    OsBackTraceInit();  //函数目前用于初始化内存泄漏检查钩子，栈回溯功能
#endif

#ifdef LOSCFG_KERNEL_LMS
    OsLmsInit();    //初始化 LMS全称为Lite Memory Sanitizer，是一种实时检测内存操作合法性的调测工具
#endif
    ret = OsMemSystemInit();    //系统堆内存初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsMemSystemInit error %d\n", ret);
        return ret;
    }

    ArchInit();     //CPU中断向量表初始化，中断接管

    ret = OsTickTimerInit();    //系统Tick时钟初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsTickTimerInit error! 0x%x\n", ret);
        return ret;
    }

    ret = OsTaskInit();         //系统任务初始化，申请控制块内存，初始化就绪链表，自动删除链表
    if (ret != LOS_OK) {
        PRINT_ERR("OsTaskInit error\n");
        return ret;
    }

#if (LOSCFG_BASE_CORE_TSK_MONITOR == 1)
    OsTaskMonInit();            //任务监控初始化
#endif

#if (LOSCFG_BASE_CORE_CPUP == 1)
    ret = OsCpupInit();         //初始化CPU占空比监控
    if (ret != LOS_OK) {
        PRINT_ERR("OsCpupInit error\n");
        return ret;
    }
#endif

#if (LOSCFG_BASE_IPC_SEM == 1)
    ret = OsSemInit();          //信号量初始化
    if (ret != LOS_OK) {
        return ret;
    }
#endif

#if (LOSCFG_BASE_IPC_MUX == 1)
    ret = OsMuxInit();          //互斥锁初始化
    if (ret != LOS_OK) {
        return ret;
    }
#endif

#if (LOSCFG_BASE_IPC_QUEUE == 1)
    ret = OsQueueInit();        //消息队列初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsQueueInit error\n");
        return ret;
    }
#endif

#if (LOSCFG_BASE_CORE_SWTMR == 1)
    ret = OsSwtmrInit();        //软件定时器初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsSwtmrInit error\n");
        return ret;
    }
#endif

#if (LOSCFG_CPUP_INCLUDE_IRQ == 1)
    ret = OsCpupDaemonInit();   //CPU占空比守护进程
    if (ret != LOS_OK) {
        PRINT_ERR("OsCpupDaemonInit error\n");
        return ret;
    }
#endif

#if (LOSCFG_FS_VFS == 1)
    ret = OsVfsInit();      //文件系统初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsVfsInit error\n");
        return ret;
    }
#endif

    ret = OsIdleTaskCreate();   //创建idle进程
    if (ret != LOS_OK) {
        return ret;
    }

#if (LOSCFG_KERNEL_TRACE == 1)
    ret = OsTraceInit();        //系统跟踪初始化
    if (ret != LOS_OK) {
        PRINT_ERR("OsTraceInit error\n");
        return ret;
    }
#endif

#if (LOSCFG_KERNEL_PM == 1)
    ret = OsPmInit();           //电源控制初始化
    if (ret != LOS_OK) {
        PRINT_ERR("Pm init failed!\n");
        return ret;
    }
#endif

#if (LOSCFG_KERNEL_LMK == 1)
    OsLmkInit();                //低内存自动Kill框架
#endif

#if (LOSCFG_PLATFORM_EXC == 1)
    OsExcMsgDumpInit();         //信号获取初始化
#endif

#if (LOSCFG_DYNLINK == 1)
    ret = LOS_DynlinkInit();        //动态链接
    if (ret != LOS_OK) {
        return ret;
    }
#endif

#if (LOSCFG_POSIX_PIPE_API == 1)
    ret = OsPipeInit();             //Pipe初始化
    if (ret != LOS_OK) {
        PRINT_ERR("Pipe init failed!\n");
        return ret;
    }
#endif

#if (LOSCFG_KERNEL_SIGNAL == 1)
    ret = OsSignalInit();           //信号初始化
    if (ret != LOS_OK) {
        PRINT_ERR("Signal init failed!\n");
        return ret;
    }
#endif

#if (LOSCFG_SECURE == 1)
    OsSyscallHandleInit();      //系统调用
    LOS_BoxStart();             //创建BOX用户任务
#endif

    return LOS_OK;
}

LOS_KernelInit函数中初始化的系统模块，多数可以根据内核配置进行增减，在lite-m目录下使用make menuconfig进行配置。

三、LOS_Start代码解析

LITE_OS_SEC_TEXT_INIT UINT32 LOS_Start(VOID)
{
    return ArchStartSchedule();     //启动任务调度
}

由于系统任务管理、调度算法，会涉及芯片平台的中断开关、任务上下文切换等，因此，下一篇文章先分析SOC Cortex-m4启动代码适配。

坚持就有收获