rt_vsnprintf 函数内部数组分配不在栈内

/**
  ******************************************************************************
  * @file     startup_at32f435_437.s
  * @version  v2.0.7
  * @date     2022-04-02
  * @brief    at32f435_437 devices vector table for gcc toolchain.
  *           this module performs:
  *           - set the initial sp
  *           - set the initial pc == reset_handler,
  *           - set the vector table entries with the exceptions isr address
  *           - configure the clock system and the external sram to
  *             be used as data memory (optional, to be enabled by user)
  *           - branches to main in the c library (which eventually
  *             calls main()).
  *           after reset the cortex-m4 processor is in thread mode,
  *           priority is privileged, and the stack is set to main.
  ******************************************************************************
  */
  .syntax unified
  .cpu cortex-m4
  .fpu softvfp
  .thumb
.global  g_pfnVectors
.global  Default_Handler
/* start address for the initialization values of the .data section.
defined in linker script */
.word  _sidata
/* start address for the .data section. defined in linker script */
.word  _sdata
/* end address for the .data section. defined in linker script */
.word  _edata
/* start address for the .bss section. defined in linker script */
.word  _sbss
/* end address for the .bss section. defined in linker script */
.word  _ebss
/* stack used for SystemInit_ExtMemCtl; always internal RAM used */
/**
 * @brief  This is the code that gets called when the processor first
 *          starts execution following a reset event. Only the absolutely
 *          necessary set is performed, after which the application
 *          supplied main() routine is called.
 * @param  None
 * @retval None
*/
    .section  .text.Reset_Handler
  .weak  Reset_Handler
  .type  Reset_Handler, %function
Reset_Handler:
/* Copy the data segment initializers from flash to SRAM */
  movs  r1, #0
  b  LoopCopyDataInit
CopyDataInit:
  ldr  r3, =_sidata
  ldr  r3, [r3, r1]
  str  r3, [r0, r1]
  adds  r1, r1, #4
LoopCopyDataInit:
  ldr  r0, =_sdata
  ldr  r3, =_edata
  adds  r2, r0, r1
  cmp  r2, r3
  bcc  CopyDataInit
  ldr  r2, =_sbss
  b  LoopFillZerobss
/* Zero fill the bss segment. */
FillZerobss:
  movs  r3, #0
  str  r3, [r2], #4
LoopFillZerobss:
  ldr  r3, = _ebss
  cmp  r2, r3
  bcc  FillZerobss
/* Call the clock system intitialization function.*/
  bl  SystemInit
/* Call static constructors */
//  bl __libc_init_array
/* Call the application's entry point.*/
  bl  entry
  bx  lr
.size  Reset_Handler, .-Reset_Handler

    __set_CONTROL(0);
    __set_MSP(stk_addr);