开机代码注释完善

    百图画鸿蒙 + 百文说内核 + 百万注源码  => 挖透鸿蒙内核源码
    鸿蒙研究站 | http://weharmonyos.com (国内)
              | https://weharmony.github.io (国外)
    oschina | https://my.oschina.net/weharmony
    博客园 | https://www.cnblogs.com/weharmony/
    知乎 | https://www.zhihu.com/people/weharmonyos
    csdn | https://blog.csdn.net/kuangyufei
    51cto | https://harmonyos.51cto.com/column/34
    掘金 | https://juejin.cn/user/756888642000808
    公众号 | 鸿蒙研究站 (weharmonyos)

arch/arm/arm/include/los_hw_cpu.h

@@ -146,12 +146,12 @@ extern "C" {
 #define TPIDRPRW            CP15_REG(c13, 0, c0, 4)    /*! PL1 only Thread ID Register | 仅PL1线程ID寄存器*/	
 
 #define MPIDR_CPUID_MASK    (0xffU)
-/// 获取当前task
+/// 获取当前task的地址
 STATIC INLINE VOID *ArchCurrTaskGet(VOID)
 {
     return (VOID *)(UINTPTR)ARM_SYSREG_READ(TPIDRPRW);//读c13寄存器
 }
-/// 设置当前task ID
+/// 向CP15 - > C13 保存当前任务的地址
 STATIC INLINE VOID ArchCurrTaskSet(VOID *val)
 {
     ARM_SYSREG_WRITE(TPIDRPRW, (UINT32)(UINTPTR)val);

arch/arm/arm/src/los_dispatch.S

@@ -283,7 +283,7 @@ FUNCTION(ArchSpinLock)	//非要拿到锁
 	strexeq r2, r1, [r0]//此时CPU被重新唤醒,尝试令lock->rawLock=1,成功写入则r2=0
 	cmpeq	r2, #0		//再来比较r2是否等于0,如果相等则获取到了锁
 	bne 	1b			//如果不相等,继续进入循环
-	dmb 				//用DMB指令来隔离，以保证缓冲中的数据已经落实到RAM中
+	dmb 				//用DMB指令来隔离，以保证缓冲中的数据已经落地到RAM中
 	bx		lr			//此时是一定拿到锁了,跳回调用ArchSpinLock函数
 
 
@@ -294,7 +294,7 @@ FUNCTION(ArchSpinTrylock)	//尝试拿锁
 	ldrex	r0, [r2]		//r2 = &lock->rawLock, 即 r0 = lock->rawLock
 	cmp 	r0, #0			//r0和0比较
 	strexeq r0, r1, [r2]	//尝试令lock->rawLock=1,成功写入则r0=0,否则 r0 =1
-	dmb 					//数据存储隔离，以保证缓冲中的数据已经落实到RAM中
+	dmb 					//数据存储隔离，以保证缓冲中的数据已经落地到RAM中
 	bx		lr				//跳回调用ArchSpinLock函数
 
 
@@ -304,7 +304,7 @@ FUNCTION(ArchSpinUnlock)	//释放锁
 	dmb 					//数据存储隔离，以保证缓冲中的数据已经落实到RAM中
 	str 	r1, [r0]		//令lock->rawLock = 0
 	dsb 					//数据同步隔离
-	sev 					//给各CPU广播事件,唤醒沉睡的CPU们
+	sev 					//sev为发送事件指令,这种事件指的是CPU核与核之间的事件,广播事件给各个CPU核
 	bx		lr				//跳回调用ArchSpinLock函数
 
 

arch/arm/arm/src/los_hw.c

@@ -44,7 +44,7 @@ CpuVendor g_cpuTable[] = {
 /* logical cpu mapping | cpu 逻辑层映射*/
 UINT64 g_cpuMap[LOSCFG_KERNEL_CORE_NUM] = {
     [0 ... LOSCFG_KERNEL_CORE_NUM - 1] = (UINT64)(-1) //统一赋值,这个赋值方式还挺别致的.
-};
+};//此处可查看鸿蒙内核源码分析(编码方式篇) https://my.oschina.net/weharmony/blog/5516143
 
 /* bit[30] is enable FPU */
 #define FP_EN (1U << 30)

arch/arm/arm/src/startup/reset_vector_mp.S

@@ -117,18 +117,18 @@ OsGetArgsAddr:
 reset_vector: //鸿蒙开机代码
     /* clear register TPIDRPRW */
     mov     r0, #0					//r0 = 0
-    mcr     p15, 0, r0, c13, c0, 4	//清除线程标识符寄存器TPIDRPRW为0
+    mcr     p15, 0, r0, c13, c0, 4	//复位线程标识符寄存器TPIDRPRW , 不复位将导致系统不能启动
     /* do some early cpu setup: i/d cache disable, mmu disabled */
-    mrc     p15, 0, r0, c1, c0, 0	//System Control Register-SCTLR
-    bic     r0, #(1<<12)			//不使能指令缓存功能
-    bic     r0, #(1<<2 | 1<<0)		//不使能数据和TLB的缓存功能(bit2) | 不使能mmu功能(bit0)
-    mcr     p15, 0, r0, c1, c0, 0
+    mrc     p15, 0, r0, c1, c0, 0	//System Control Register-SCTLR | 读取系统控制寄存器内容
+    bic     r0, #(1<<12)			//禁用指令缓存功能
+    bic     r0, #(1<<2 | 1<<0)		//禁用数据和TLB的缓存功能(bit2) | mmu功能(bit0)
+    mcr     p15, 0, r0, c1, c0, 0	//写系统控制寄存器
 
     /* enable fpu+neon 一些系统寄存器的操作
     | 使能浮点运算(floating point unit)和 NEON就是一种基于SIMD思想的ARM技术，相比于ARMv6或之前的架构，
     NEON结合了64-bit和128-bit的SIMD指令集，提供128-bit宽的向量运算(vector operations)*/
 #ifndef LOSCFG_TEE_ENABLE        //Trusted Execution Environment   可信执行环境
-    MRC    p15, 0, r0, c1, c1, 2 //Non-Secure Access Control Register - NSACR
+    MRC    p15, 0, r0, c1, c1, 2 //非安全模式访问寄存器 (Non-Secure Access Control Register - NSACR)
     ORR    r0, r0, #0xC00        //使能安全和非安全访问协处理器10和11(Coprocessor 10和11)
     BIC    r0, r0, #0xC000       //设置bit15为0，不会影响修改CPACR.ASEDIS寄存器位（控制Advanced SIMD功能）| bit14 reserved
     MCR    p15, 0, r0, c1, c1, 2
@@ -137,22 +137,22 @@ reset_vector: //鸿蒙开机代码
     MCR    p15, 0, r0, c1, c0, 2
     ISB
 #endif
-    MOV    r3, #0x40000000	    //设置FPEXC的EN位来使能FPU
-    VMSR   FPEXC, r3
+    MOV    r3, #0x40000000	    //EN, bit[30] 设置FPEXC的EN位来使能FPU
+    VMSR   FPEXC, r3			//浮点异常控制寄存器 (Floating-Point Exception Control register | B4.1.57) 
 
     /* r11: delta of physical address and virtual address | 内核运行虚拟地址和物理地址之间的差值 */
-    adr     r11, pa_va_offset //获取pa_va_offset变量的当前物理地址
-                              /* adr是伪指令被汇编为sub机器指令；程序链接过程中pa_va_offset标识虚拟地址和adr伪指令的虚拟									
-                               * 地址是相对固定的，所以二者偏移量就是确定的offset值；adr伪指令在Rn不为pc时结果就如sub Rn pc #offset，即									
-                               * sub R11 pc #offset //pc是当前指令的物理地址
+    adr     r11, pa_va_offset //获取pa_va_offset变量物理地址，由于这时候mmu已经被关闭，所以这个值就表示pa_va_offset变量的物理地址。
+                              /*adr 是一条小范围的地址读取伪指令,它将基于PC的相对偏移的地址值读到目标寄存器中。
+                               *编译源程序时，汇编器首先计算当前PC值（当前指令位置）到exper的距离,然后用一条ADD或者SUB指令替换这条伪指令，
+                               *例如:ADD register,PC,#offset_to_exper 注意，标号exper与指令必须在同一代码段
                                */
-    ldr     r0, [r11]		  //r0 = *r11 获取pa_va_offset变量的虚拟地址
-    sub     r11, r11, r0
+    ldr     r0, [r11]		  //r0 = *r11 获取pa_va_offset变量虚拟地址
+    sub     r11, r11, r0	  //物理地址-虚拟地址 = 偏移量 放入r11
 
     mrc     p15, 0, r12, c0, c0, 5      /* Multiprocessor Affinity Register-MPIDR */
-    and     r12, r12, #MPIDR_CPUID_MASK
+    and     r12, r12, #MPIDR_CPUID_MASK //掩码过滤
     cmp     r12, #0	                    //主控核0判断
-    bne     secondary_cpu_init
+    bne     secondary_cpu_init	//初始化CPU次核
 	/*
 	 * adr是小范围的地址读取伪指令,它将基于PC寄存器相对偏移的地址值读取到寄存器中，
 	 * 例如: 0x00000004 	 : adr     r4, __exception_handlers
@@ -164,9 +164,9 @@ reset_vector: //鸿蒙开机代码
      * 一般也就是一一映射，也就是物理地址和虚拟地址值是一样的，所以可以认为内核加载地址值是物理地址
      */
     /* if we need to relocate to proper location or not | 如果需要重新安装到合适的位置*/
-    adr     r4, __exception_handlers            /* r4: base of load address */
-    ldr     r5, =SYS_MEM_BASE                   /* r5: base of physical address */
-    subs    r12, r4, r5                         /* r12: delta of load address and physical address */
+    adr     r4, __exception_handlers            /* r4: base of load address | 加载基址*/
+    ldr     r5, =SYS_MEM_BASE                   /* r5: base of physical address | 物理基址*/
+    subs    r12, r4, r5                         /* r12: delta of load address and physical address | 二者偏移量*/
     beq     reloc_img_to_bottom_done            /* if we load image at the bottom of physical address | 不相等就需要重定位 */
 	
     /* we need to relocate image at the bottom of physical address */
@@ -223,7 +223,7 @@ init_mmu_done:
     rsb     r7, r11, r6, lsl #20                /* r7: va */
     str     r12, [r4, r7, lsr #(20 - 2)]        /* jumpTable[vaIndex] = pt entry */
 
-    bl      mmu_setup                           /* set up the mmu */
+    bl      mmu_setup                           /* set up the mmu | 设置MMU*/
 #endif
     /* clear out the interrupt and exception stack and set magic num to check the overflow */
     ldr     r0, =__svc_stack	    //中断栈的底部,从这里可以看出中断栈处于最高位

kernel/base/core/los_smp.c

@@ -40,7 +40,7 @@
 
 #ifdef LOSCFG_KERNEL_SMP
 STATIC struct SmpOps *g_smpOps = NULL;
-
+/// 多核中次级CPU核初始化,每个核都会调用一次
 STATIC VOID OsSmpSecondaryInit(VOID *arg)
 {
     UNUSED(arg);
@@ -49,12 +49,12 @@ STATIC VOID OsSmpSecondaryInit(VOID *arg)
     OsSwtmrInit();
 #endif
 
-    OsIdleTaskCreate();
+    OsIdleTaskCreate();//每个核都有一个空闲任务
     OsInitCall(LOS_INIT_LEVEL_KMOD_TASK);
 
     OsSchedStart();
 }
-
+/// 设置多核操作接口, 通过外部注册
 VOID LOS_SmpOpsSet(struct SmpOps *ops)
 {
     g_smpOps = ops;

kernel/base/include/los_sched_pri.h

@@ -461,7 +461,7 @@ STATIC INLINE LosTaskCB *OsCurrTaskGet(VOID)
 {
     return (LosTaskCB *)ArchCurrTaskGet();
 }
-
+/// 注意任务地址由硬件保存,见于 CP15 | TPIDRPRW
 STATIC INLINE VOID OsCurrTaskSet(LosTaskCB *task)
 {
     ArchCurrTaskSet(task);

kernel/base/sched/los_sched.c

@@ -307,14 +307,14 @@ VOID OsSchedStart(VOID)
     newTask->taskStatus |= OS_TASK_STATUS_RUNNING;
 
 #ifdef LOSCFG_KERNEL_SMP
-    /*
+    /* 注意：需要设置当前cpu，以防第一个任务删除失败，因为这个标志与真实的当前cpu不匹配
      * attention: current cpu needs to be set, in case first task deletion
      * may fail because this flag mismatch with the real current cpu.
      */
-    newTask->currCpu = cpuid;
+    newTask->currCpu = cpuid;//记录本次运行交给哪个CPU核
 #endif
 
-    OsCurrTaskSet((VOID *)newTask);
+    OsCurrTaskSet((VOID *)newTask);//设置新任务,背后的逻辑是将新任务的地址交给硬件保存
 
     newTask->startTime = OsGetCurrSchedTimeCycle();
 

kernel/common/los_config.c

@@ -70,10 +70,10 @@ LITE_OS_SEC_TEXT_INIT STATIC UINT32 EarliestInit(VOID)
     /* Must be placed at the beginning of the boot process *///必须放在启动过程的开头
     OsSetMainTask();//为每个CPU核设置临时主任务
     OsCurrTaskSet(OsGetMainTask());//设置当前任务
-    OsSchedRunqueueInit();
+    OsSchedRunqueueInit();//初始化调度队列
 
-    g_sysClock = OS_SYS_CLOCK;
-    g_tickPerSecond =  LOSCFG_BASE_CORE_TICK_PER_SECOND;
+    g_sysClock = OS_SYS_CLOCK; //设置系统时钟
+    g_tickPerSecond =  LOSCFG_BASE_CORE_TICK_PER_SECOND; // 设置TICK间隔
 
     return LOS_OK;
 }
@@ -88,10 +88,10 @@ LITE_OS_SEC_TEXT_INIT STATIC UINT32 ArchEarlyInit(VOID)
 #endif
 
 #ifdef LOSCFG_PLATFORM_HWI
-    OsHwiInit();
+    OsHwiInit(); // 硬中断初始化
 #endif
 
-    OsExcInit();
+    OsExcInit(); // 异常初始化
 
     ret = OsTickInit(g_sysClock, LOSCFG_BASE_CORE_TICK_PER_SECOND);
     if (ret != LOS_OK) {

kernel/include/los_smp.h

-/*
- * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
- * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this list of
- *    conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright notice, this list
- *    of conditions and the following disclaimer in the documentation and/or other materials
- *    provided with the distribution.
- *
- * 3. Neither the name of the copyright holder nor the names of its contributors may be used
- *    to endorse or promote products derived from this software without specific prior written
- *    permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
- * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
- * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
+/*
+ * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
+ * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *    of conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used
+ *    to endorse or promote products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
 
 #ifndef _LOS_SMP_H
 #define _LOS_SMP_H
 
 #include "smp.h"
 
-#ifdef __cplusplus
-#if __cplusplus
-extern "C" {
-#endif /* __cplusplus */
+#ifdef __cplusplus
+#if __cplusplus
+extern "C" {
+#endif /* __cplusplus */
 #endif /* __cplusplus */
 
 VOID LOS_SmpOpsSet(struct SmpOps *ops);
 VOID OsSmpInit(VOID);
 
-#ifdef __cplusplus
-#if __cplusplus
-}
-#endif /* __cplusplus */
-#endif /* __cplusplus */
-
+#ifdef __cplusplus
+#if __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* __cplusplus */
+
 #endif /* _LOS_SMP_H */
 

platform/board.ld.S

@@ -28,13 +28,6 @@
  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-
-#include "los_vm_zone.h"
-#define TEXT_BASE  KERNEL_VADDR_BASE //代码区为内核起始地址
-
-OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
-OUTPUT_ARCH(arm)
-
 /***********************************************
 本文件经过
 python build.py ipcamera_hi3516dv300 
@@ -81,6 +74,14 @@ ATTR ：定义该存储区域的属性。ATTR属性内可以出现以下7 个字
 ORIGIN ：关键字，区域的开始地址，可简写成org 或o
 LENGTH ：关键字，区域的大小，可简写成len 或l
 */
+
+#include "los_vm_zone.h"
+#define TEXT_BASE  KERNEL_VADDR_BASE //代码区为内核起始地址
+
+OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
+OUTPUT_ARCH(arm)
+
+
 MEMORY
 { //ram,sram为存储区域的名字,可以随意取
     ram : ORIGIN = KERNEL_VADDR_BASE, LENGTH = KERNEL_VADDR_SIZE
@@ -89,7 +90,7 @@ MEMORY
 }
 SECTIONS
 {
-    /DISCARD/ : { *(.comment .note) }
+    /DISCARD/ : { *(.comment .note) } //过滤掉 .comment .note 段
 
     .ram_vectors TEXT_BASE : {
         __ram_vectors_vma = .;

zzz/git/push.sh

 git add -A
-git commit -m  ' 同步官方源码 标准库(musl , newlib) 目录调整
+git commit -m  ' 开机代码注释完善
     百图画鸿蒙 + 百文说内核 + 百万注源码  => 挖透鸿蒙内核源码
     鸿蒙研究站 | http://weharmonyos.com (国内) 
               | https://weharmony.github.io (国外)