修改说明

1. 固定 --target=arm-arm-none-eabi

   原因：
   MDK的armclang仅支持此target。

   C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\ARMCLANG\bin>armclang --target=aarch64-arm-none-eabi -mcpu=list
   The following arguments to option 'mcpu' can be selected:
   
   C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\ARMCLANG\bin>armclang --target=arm-arm-none-eabi -mcpu=list
   The following arguments to option 'mcpu' can be selected:
     -mcpu=cortex-m0
     -mcpu=cortex-m0plus
     -mcpu=cortex-m1
     -mcpu=cortex-m3
     -mcpu=cortex-m4
     -mcpu=cortex-m7
     -mcpu=cortex-m23
     -mcpu=cortex-m33
     -mcpu=cortex-m35p
     -mcpu=cortex-m52
     -mcpu=cortex-m55
     -mcpu=cortex-m85
     -mcpu=cortex-r4
     -mcpu=cortex-r4f
     -mcpu=sc000
     -mcpu=sc300
     -mcpu=star-mc1
   

   其他CPU使用aarch64-arm-none-eabi会提示许可证问题导致编译失败。

   C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\ARMCLANG\bin>armclang -v
   Product: MDK Plus 5.42
   Component: Arm Compiler for Embedded 6.23
   Tool: armclang [5f103000]
   
   Target: unspecified-arm-none-none
   armclang: fatal error: no target architecture given; use --target=arm-arm-none-eabi or --target=aarch64-arm-none-eabi
   
   C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\ARMCLANG\bin>armclang --target=aarch64-arm-none-eabi C:/Users/Pochita/Desktop/test.c -o C:/Users/Pochita/Desktop/test.o
   armclang: error: ARMv8a is not available with the current toolkit edition and license. Check that your licensing and toolkit configuration is set up correctly, using the information available at https://developer.arm.com/tools-and-software/software-development-tools/license-management/resources/product-and-toolkit-configuration
   Check that your license details are correct in the License Management dialog of MDK. Additional information is available at:
    http://www.keil.com/support/man/docs/license/license_management.htm
    If you need further help, provide this complete error message to your supplier or to Arm via https://services.arm.com/support/s/contactsupport
   
    - ARMLMD_LICENSE_FILE: unset
    - LM_LICENSE_FILE: unset
    - ARM_PRODUCT_DEF: unset
    - ARM_PRODUCT_PATH: unset
    - ARM_TOOL_VARIANT: unset
    - Product location: C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\sw\mappings
    - Toolchain location: C:\Users\Pochita\AppData\Local\Programs\Keil_v5\ARM\ARMCLANG\bin
    - Selected tool variant: mdk_std
      Product: MDK Plus 5.42
      Component: Arm Compiler for Embedded 6.23
      Tool: armclang [5f103000]
   
   armclang: error: unsupported argument 'aarch64-arm-none-eabi' to option '--target='
   

2. 添加 -masm=auto 汇编参数

   原因：

   当编译器版本是6.13及以上时，启动代码可能还在使用armasm语法，此时要使用-masm=armasm指定汇编器，否则启动代码报错。armclang提供了-masm=auto来检测汇编代码的语法并自动选择汇编器。（官方说明）

3. 链接器参数格式调整

   原因：

   • 实际验证表明armlink不区分大小写（如--cpu=cortex-m7和--cpu=Cortex-M7等效）
   • 统一使用等号格式（--cpu=<name>）以提高可读性，与ARM官方示例保持一致（官方说明）

此说明直接对应代码变更，且通过：

• MDK v5.42a + ARMCompiler6.23 + Cortex-M7 硬件实测

thanks