diff --git a/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_dispatch.S b/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_dispatch.S
index c798df06..0f9074fa 100644
--- a/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_dispatch.S
+++ b/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_dispatch.S
@@ -107,14 +107,14 @@
 
 HalTaskContextSwitch:
     PUSH_ALL_REG
-
+    // a0保存着 mstatus
     // clear mpie
-    li   a2, RISCV_MSTATUS_MPIE
-    not  a2, a2
+    li   a2, RISCV_MSTATUS_MPIE // 0x00000080
+    not  a2, a2 // 0xffffff7f
     and  a0, a0, a2
 
     // get mie
-    andi a1, a0, RISCV_MSTATUS_MIE
+    andi a1, a0, RISCV_MSTATUS_MIE // 0x00000008
 
     // must be in machine mode
     ori  a1, a1, 0x180
@@ -125,24 +125,25 @@ HalTaskContextSwitch:
     li   a2, RISCV_MSTATUS_MIE
     not  a2, a2
     and  a0, a0, a2
-
+    // a0 清除 mie后的 mstatus
     SREG a0, 16 * REGBYTES(sp)
-    // 把当前程序地址压栈，用于异常地址
+    // 返回地址
     SREG ra, 17 * REGBYTES(sp)
 
     la   a1, g_losTask
-    lw   a0, 0(a1)
-    sw   sp, TASK_CB_KERNEL_SP(a0)
+    lw   a0, 0(a1) // g_losTask->runTask
+    // 把当前sp指针保存到 g_losTask->runTask->stackPointer
+    sw   sp, TASK_CB_KERNEL_SP(a0) // TASK_CB_KERNEL_SP==0
 
-    lw   a0, 4(a1)
-    sw   a0, 0(a1)
+    lw   a0, 4(a1) // g_losTask->newTask
+    sw   a0, 0(a1) // g_losTask->runTask=g_losTask->newTask
 
 HalStartToRun:
     la   a1, g_losTask
-    lw   a0, 4(a1)
+    lw   a0, 4(a1) // g_losTask->newTask
 
 // retireve stack pointer
-    lw      sp, TASK_CB_KERNEL_SP(a0)
+    lw      sp, TASK_CB_KERNEL_SP(a0) // sp=g_losTask->newTask->stackPointer
 
 // enable global interrupts
     lw      t0, 16 * REGBYTES(sp)
@@ -150,7 +151,7 @@ HalStartToRun:
 
 // retrieve the address at which exception happened
     lw      t0, 17 * REGBYTES(sp)
-    csrw    mepc, t0
+    csrw    mepc, t0 // 修改mepc，随后调用mret就会跳转到这个地址
 
 // retrieve the registers
     POP_ALL_REG
diff --git a/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_exc.S b/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_exc.S
index 7a504ff6..2e2cd62d 100644
--- a/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_exc.S
+++ b/kernel/liteos_m/arch/risc-v/riscv32/gcc/los_exc.S
@@ -145,14 +145,15 @@ HalTrapEntry:
     csrw  mscratch, sp
     la    t0, g_excInfo
     lh    t1, 0(t0)
+    // 不为0时跳转
     bnez  t1, 1f
     la    sp, __except_stack_top
 1:
     addi  t1, t1, 0x1
-    sh    t1, 0(t0)
+    sh    t1, 0(t0) // g_excInfo->nestCnt++
     call  HalExcEntry
     la    t0, g_excInfo
-    sh    zero, 0(t0)
+    sh    zero, 0(t0) // g_excInfo->nestCnt=0
     csrr  sp, mscratch
     addi  sp, sp, 4 * REGBYTES
     lw    t0, 16 * REGBYTES(sp)
@@ -170,19 +171,28 @@ HalTrapEntry:
 .global HalTrapVector
 .equ TRAP_INTERRUPT_MODE_MASK, 0x80000000
 .align 4
+// cpu产生异常时会自动跳转到这个地址
+// 产生中断时硬件会自动把返回地址保存到mepc中
+// 可调用mret将mepc恢复到pc中
 HalTrapVector:
     PUSH_CALLER_REG
+    // mcause保存异常原因 读取到a0中
     csrr  a0, mcause
     li    a1, TRAP_INTERRUPT_MODE_MASK
-    li    a2, MCAUSE_INT_ID_MASK
+    li    a2, MCAUSE_INT_ID_MASK // 0x7FFFFFFF
     and   a1, a0, a1
     and   a0, a2, a0
+    // 等于0时跳转
     beqz  a1, HalTrapEntry
     // 异常处理退出不会返回到这里
+    // 保存线程sp指针
     csrw  mscratch, sp
     la    sp, __start_and_irq_stack_top
+    // 处理中断 a0 保存着异常原因，如果最高位为0 则为中断号
     jal   HalHwiInterruptDone
+    // 恢复线程sp指针
     csrr  sp, mscratch
+    // 切线程都是在线程栈中完成的
     call  HalIrqEndCheckNeedSched
     // HalIrqEndCheckNeedSched如果切换了任务，这里会从切换后的任务返回
     POP_CALLER_REG