Migration Guide

[中文]

OS Migration Introduction

This chapter takes the Hong Meng OS migration of BK7256 RISC-V architecture as an example

• Operating system kernel source code path:components/os_source/

• The operating system kernel source code is modified in ‘components/os_source/CMakeLists.txt’ and added to the Armino platform for compilation.

• Define operating system related macros in ‘components/bk_rtos/Kconfig’

  menu "LITEOS_M"
  
      config LITEOS_M
          bool "liteos_m"
          default n
  
      config LITEOS_M_V3
          bool "liteos_m v3.0.1-LTS"
          default n
  
  
      config LITEOS_M_BK
          depends on LITEOS_M_V3
              bool "liteos_m bk adapter"
              default n
  endmenu
  

• Add Harmony Project：projects/harmony

• Configure macro definitions related to the operating system：projects/harmony/sdkconfig.defaults

  # LITEOS_M
  CONFIG_LITEOS_M_V3=y
  CONFIG_LITEOS_M_BK=y
  
  # FreeRTOS
  CONFIG_FREERTOS=n
  CONFIG_FREERTOS_V9=n
  CONFIG_FREERTOS_V10=n
  

• Implement OS abstract layer interface：components/bk_rtos/liteos_m_v3/rtos_pub.c

• Create system startup assembly code：middleware/arch/riscv/boot_vectors_liteos_m.S

• Key register of RISC-V: Set interrupt and exception entries：

  /* Initial machine trap-vector Base.*/
  la t0, HalTrapVector
  csrw mtvec, t0
  

• Adapt exception handling function：trap_handler

  HalTrapEntry modify in components/os_source/liteos_m_v3/kernel/arch/risc-v/riscv32/gcc/los_exc.S

• Interrupt entry：HalHwiInterruptDone

• Register the external interrupt handling function of the Armino platform：vPortSetupMEXTInterrupt

• Register the MTIME interrupt handling function of the Armino platform：vPortSetupTimerInterrupt

• Register external interrupts and MTIME interrupts before scheduling

  LITE_OS_SEC_TEXT_INIT UINT32 HalStartSchedule(VOID)
  {
      (VOID)LOS_IntLock();
      OsSchedStart();
  
  #if CONFIG_LITEOS_M_BK
      vPortSetupTimerInterrupt();
      vPortSetupMEXTInterrupt();
  #endif
  
      HalStartToRun();
      return LOS_OK; /* never return */
  }
  

• BK7256 RISC-V The mtime register is 64 bits. When adapting, you should pay attention to the definition type of the maximum value.