10 memheap内存分配释放问题

发布于 2025-04-21 18:24:44 浏览：136 订阅该版

[tocm]

## 配置描述：
硬件平台STM32F767IIT6，FMC挂载了2块SRAM，8位数据宽度，共用数据线和地址线，使用NE3和NE4片选切换，对应起始地址分别为：0x68000000和0x6C000000，IDE：RT-Thread Studio，系统版本：4.1.1，使用memheap作为内存堆，已经启用RT_USING_MEMHEAP_AS_HEAP
## 问题描述
使用rt_malloc分配的内存大小和预期不符，使用rt_free释放后内存大小没有恢复反而变的更少了
## 链接文件如下
```c
/*
 * linker script for STM32F767II with GNU ld
 */

/* Program Entry, set to mark it as "used" and avoid gc */
MEMORY
{
ROM (rx) : ORIGIN =0x08020000,LENGTH =1920k
RAM (rw) : ORIGIN =0x20020000,LENGTH =384k
EX_SRAM1 (rw) : ORIGIN =0x68000000,LENGTH =1024k
EX_SRAM2 (rw) : ORIGIN =0x6C000000,LENGTH =1024k
}
ENTRY(Reset_Handler)
_system_stack_size = 0x400;

SECTIONS
{
    .text :
    {
        . = ALIGN(4);
        _stext = .;
        KEEP(*(.isr_vector))            /* Startup code */

. = ALIGN(4);
        *(.text)                        /* remaining code */
        *(.text.*)                      /* remaining code */
        *(.rodata)                      /* read-only data (constants) */
        *(.rodata*)
        *(.glue_7)
        *(.glue_7t)
        *(.gnu.linkonce.t*)

/* section information for finsh shell */
        . = ALIGN(4);
        __fsymtab_start = .;
        KEEP(*(FSymTab))
        __fsymtab_end = .;

. = ALIGN(4);
        __vsymtab_start = .;
        KEEP(*(VSymTab))
        __vsymtab_end = .;

/* section information for utest */
        . = ALIGN(4);
        __rt_utest_tc_tab_start = .;
        KEEP(*(UtestTcTab))
        __rt_utest_tc_tab_end = .;

/* section information for at server */
        . = ALIGN(4);
        __rtatcmdtab_start = .;
        KEEP(*(RtAtCmdTab))
        __rtatcmdtab_end = .;
        . = ALIGN(4);

/* section information for initial. */
        . = ALIGN(4);
        __rt_init_start = .;
        KEEP(*(SORT(.rti_fn*)))
        __rt_init_end = .;

. = ALIGN(4);

PROVIDE(__ctors_start__ = .);
        KEEP (*(SORT(.init_array.*)))
        KEEP (*(.init_array))
        PROVIDE(__ctors_end__ = .);

. = ALIGN(4);

_etext = .;
    } > ROM = 0

/* .ARM.exidx is sorted, so has to go in its own output section.  */
    __exidx_start = .;
    .ARM.exidx :
    {
        *(.ARM.exidx* .gnu.linkonce.armexidx.*)

/* This is used by the startup in order to initialize the .data secion */
        _sidata = .;
    } > ROM
    __exidx_end = .;

/* .data section which is used for initialized data */

.data : AT (_sidata)
    {
        . = ALIGN(4);
        /* This is used by the startup in order to initialize the .data secion */
        _sdata = . ;

*(.data)
        *(.data.*)
        *(.gnu.linkonce.d*)

PROVIDE(__dtors_start__ = .);
        KEEP(*(SORT(.dtors.*)))
        KEEP(*(.dtors))
        PROVIDE(__dtors_end__ = .);

. = ALIGN(4);
        /* This is used by the startup in order to initialize the .data secion */
        _edata = . ;
    } >RAM

.stack : 
    {
        . = ALIGN(4);
        _sstack = .;
        . = . + _system_stack_size;
        . = ALIGN(4);
        _estack = .;
    } >RAM

__bss_start = .;
    .bss :
    {
        . = ALIGN(4);
        /* This is used by the startup in order to initialize the .bss secion */
        _sbss = .;

*(.bss)
        *(.bss.*)
        *(COMMON)

. = ALIGN(4);
        /* This is used by the startup in order to initialize the .bss secion */
        _ebss = . ;
        
        *(.bss.init)
    } > RAM
    __bss_end = .;

/* sram section */
    /* 动态内存堆 */
    .sram (NOLOAD): 
    {
        . = ALIGN(4);
        _ssram = .;
        *(.sram)
        *(.sram.*)
        . = ALIGN(4);
        _esram = .;
    } > EX_SRAM1

/* sram2 section */
    .sram2_data :
    {
        . = ALIGN(4);
        _ssram2_data = .;
        *(.sram2.data)
        . = ALIGN(4);
        _esram2_data = .;
    } > ROM

.sram2_bss (NOLOAD):
    {
        . = ALIGN(4);
        _ssram2_bss = .;
        *(.sram2.bss)
        . = ALIGN(4);
        _esram2_bss = .;
    } > EX_SRAM2

.sram2 :
    {
        . = ALIGN(4);
        _ssram2 = .;
        *(.sram2)
        . = ALIGN(4);
        _esram2 = .;
    } > EX_SRAM2
    _end = .;
    
    /* Stabs debugging sections.  */
    .stab          0 : { *(.stab) }
    .stabstr       0 : { *(.stabstr) }
    .stab.excl     0 : { *(.stab.excl) }
    .stab.exclstr  0 : { *(.stab.exclstr) }
    .stab.index    0 : { *(.stab.index) }
    .stab.indexstr 0 : { *(.stab.indexstr) }
    .comment       0 : { *(.comment) }
    /* DWARF debug sections.
     * Symbols in the DWARF debugging sections are relative to the beginning
     * of the section so we begin them at 0.  */
    /* DWARF 1 */
    .debug          0 : { *(.debug) }
    .line           0 : { *(.line) }
    /* GNU DWARF 1 extensions */
    .debug_srcinfo  0 : { *(.debug_srcinfo) }
    .debug_sfnames  0 : { *(.debug_sfnames) }
    /* DWARF 1.1 and DWARF 2 */
    .debug_aranges  0 : { *(.debug_aranges) }
    .debug_pubnames 0 : { *(.debug_pubnames) }
    /* DWARF 2 */
    .debug_info     0 : { *(.debug_info .gnu.linkonce.wi.*) }
    .debug_abbrev   0 : { *(.debug_abbrev) }
    .debug_line     0 : { *(.debug_line) }
    .debug_frame    0 : { *(.debug_frame) }
    .debug_str      0 : { *(.debug_str) }
    .debug_loc      0 : { *(.debug_loc) }
    .debug_macinfo  0 : { *(.debug_macinfo) }
    /* SGI/MIPS DWARF 2 extensions */
    .debug_weaknames 0 : { *(.debug_weaknames) }
    .debug_funcnames 0 : { *(.debug_funcnames) }
    .debug_typenames 0 : { *(.debug_typenames) }
    .debug_varnames  0 : { *(.debug_varnames) }
}
```
## 启动文件如下，省去最后部分中断描述
```c
/**
  ******************************************************************************
  * @file      startup_stm32f767xx.s
  * @author    MCD Application Team
  * @brief     STM32F767xx Devices vector table for GCC based toolchain. 
  *            This module performs:
  *                - Set the initial SP
  *                - Set the initial PC == Reset_Handler,
  *                - Set the vector table entries with the exceptions ISR address
  *                - Branches to main in the C library (which eventually
  *                  calls main()).
  *            After Reset the Cortex-M7 processor is in Thread mode,
  *            priority is Privileged, and the Stack is set to Main.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2016 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
    
  .syntax unified
  .cpu cortex-m7
  .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
/* sram2 data start and end addresses */
.word _ssram2_data
.word _esram2_data
/* sram2 bss start and end addresses */
.word _ssram2_bss
.word _esram2_bss
/* sram2 start and end addresses */
.word _ssram2
.word _esram2
/* 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:  
  ldr   sp, =_estack      /* set stack pointer */

/* Copy the data segment initializers from flash to SRAM */  
  ldr r0, =_sdata
  ldr r1, =_edata
  ldr r2, =_sidata
  movs r3, #0
  b LoopCopyDataInit

CopyDataInit:
  ldr r4, [r2, r3]
  str r4, [r0, r3]
  adds r3, r3, #4

LoopCopyDataInit:
  adds r4, r0, r3
  cmp r4, r1
  bcc CopyDataInit
  
/* Zero fill the bss segment. */
  ldr r2, =_sbss
  ldr r4, =_ebss
  movs r3, #0
  b LoopFillZerobss

FillZerobss:
  str  r3, [r2]
  adds r2, r2, #4

LoopFillZerobss:
  cmp r2, r4
  bcc FillZerobss

/* Configure FMC Controller */
 /* bl DRV_SRAM_Init */

/* Initialize SRAM2 Data */
/*
    ldr r0, =_ssram2
    ldr r1, =_esram2
    ldr r2, =_ssram2_data
    ldr r3, =_esram2_data
    bl rt_copy_to_sram2
    */
    /*
    ldr r0, =_ssram2
    ldr r1, =_esram2_data
    ldr r2, =_ssram2_data
    bl rt_copy_to_sram2
    */

/* Zero fill the SRAM2 BSS segment. */
    ldr r2, =_ssram2_bss
    ldr r4, =_esram2_bss
    movs r3, #0
    b LoopFillZerobssSRAM2

FillZerobssSRAM2:
    str r3, [r2]
    adds r2, r2, #4

LoopFillZerobssSRAM2:
    cmp r2, r4
    bcc FillZerobssSRAM2

/* Call the clock system initialization 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

/**
 * @brief  This is the code that gets called when the processor receives an 
 *         unexpected interrupt.  This simply enters an infinite loop, preserving
 *         the system state for examination by a debugger.
 * @param  None     
 * @retval None       
*/
    .section  .text.Default_Handler,"ax",%progbits
Default_Handler:
Infinite_Loop:
  b  Infinite_Loop
  .size  Default_Handler, .-Default_Handler
/******************************************************************************
*
* The minimal vector table for a Cortex M7. Note that the proper constructs
* must be placed on this to ensure that it ends up at physical address
* 0x0000.0000.
* 
*******************************************************************************/
   .section  .isr_vector,"a",%progbits
  .type  g_pfnVectors, %object
  .size  g_pfnVectors, .-g_pfnVectors
   
   
g_pfnVectors:
  .word  _estack
  .word  Reset_Handler

.word  NMI_Handler
  .word  HardFault_Handler
  .word  MemManage_Handler
  .word  BusFault_Handler
  .word  UsageFault_Handler
  .word  0
  .word  0
  .word  0
  .word  0
  .word  SVC_Handler
  .word  DebugMon_Handler
  .word  0
  .word  PendSV_Handler
  .word  SysTick_Handler
  
  /* External Interrupts */
  .word     WWDG_IRQHandler                   /* Window WatchDog              */
  .word     PVD_IRQHandler                    /* PVD through EXTI Line detection */
  .word     TAMP_STAMP_IRQHandler             /* Tamper and TimeStamps through the EXTI line */
  .word     RTC_WKUP_IRQHandler               /* RTC Wakeup through the EXTI line */
  .word     FLASH_IRQHandler                  /* FLASH                        */
  .word     RCC_IRQHandler                    /* RCC                          */
```
## memheap初始化代码
```c
/* USER CODE BEGIN 0 */
#define RAM_HEAP_EX_START           (0x68000000)
#define RAM_HEAP_EX_SIZE            (1024 * 1024)
#define RAM_HEAP_EX_END             (RAM_EX_START + RAM_EX_SIZE)
	
struct rt_memheap ex_ram_heap;
int DRV_EX_SRAM_Register(void)
{
    rt_memheap_init(&ex_ram_heap,"SRAM EX",(void*)RAM_HEAP_EX_START,RAM_HEAP_EX_SIZE);
    return 0;
}
INIT_COMPONENT_EXPORT(DRV_EX_SRAM_Register);
```
## 关键测试代码
```c
static char *G_pDataBuf;
static void cmd_debug(int argc, char *argv[])
{
    rt_int32_t cnt = 0;
    if (argc < 2)
    {
        debug_test_usage();
        return ;
    }
    if(argc>=3){
        cnt = atoi(argv[2]);
        log_printf("cnt:%d",cnt);
        if (0 == rt_strcmp("malloc", argv[1]))
        {
            G_pDataBuf = rt_malloc(cnt*4);
            if(G_pDataBuf!=RT_NULL){
                log_printf("Allocated %d bytes memory.",cnt*4);
            }
        }
        else if (0 == rt_strcmp("calloc", argv[1]))
        {
            G_pDataBuf = rt_calloc(1,cnt*4);
            if(G_pDataBuf!=RT_NULL){
                log_printf("Allocated %d bytes memory.",cnt*4);
            }
        }
    }
    else if(argc==2){
        if (0 == rt_strcmp("free", argv[1]))
        {
            rt_free(G_pDataBuf);
            log_printf("free done");
        }
    }
    else
    {
        debug_test_usage();
        return;
    }
}
MSH_CMD_EXPORT(cmd_debug, cmd debug);
```
## 日志如下
内存分配前内存情况如下所示
```c
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     221988     151924        71780
msh />
```
使用rt_malloc分配4字节的内存后内存情况如下所示，可以看到实际分配了400字节
```c
msh />cmd_debug malloc 1
1.[1970-01-01 08:01:40.688][debug_thread.c 986]:cnt:1
2.[1970-01-01 08:01:40.693][debug_thread.c 991]:Allocated 4 bytes memory.
msh />free
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     221988     151924        71380
msh />
```
使用rt_free释放后，内存情况如下所示
```c
msh />cmd_debug free    
3.[1970-01-01 08:02:53.608][debug_thread.c 1006]:free done
msh />free
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     221988     151924        71292
msh />
```
可以看到分配的内存和实际不符，且执行释放后内存没有恢复反而变的更少了，不知为何，请各位大佬帮忙看看是什么原因，感谢。

3 个回答

张世争 2025-04-22

学以致用

xingchen8910 2025-04-22

这家伙很懒，什么也没写！

请登录后再发布评论，点击登录

追加回复

踩姑娘的小蘑菇 2025-04-22

这家伙很懒，什么也没写！

xingchen8910 2025-04-22

这家伙很懒，什么也没写！

请登录后再发布评论，点击登录

追加回复

rv666 认证专家 2025-04-22

用GDB调试人生

xingchen8910 2025-04-22

这家伙很懒，什么也没写！

内存管理配置如下
![screenshot_1745289267105.png](https://oss-club.rt-thread.org/uploads/20250422/cf86cd7e50df2046a0c22216b3d32f09.png)
修改后的测试代码如下
```c
static void cmd_debug(int argc, char *argv[])
{
    rt_int32_t cnt = 0;
    if (argc < 2)
    {
        debug_test_usage();
        return ;
    }
    if(argc>=3){
        cnt = atoi(argv[2]);
        log_printf("cnt:%d",cnt);
        if (0 == rt_strcmp("malloc", argv[1]))
        {
            cmd_free(RT_NULL,RT_NULL);
            G_pDataBuf = rt_malloc(cnt*4);
            if(G_pDataBuf!=RT_NULL){
                log_printf("Allocated %d bytes memory.",cnt*4);
                cmd_free(RT_NULL,RT_NULL);
            }
        }
        else if (0 == rt_strcmp("calloc", argv[1]))
        {
            cmd_free(RT_NULL,RT_NULL);
            G_pDataBuf = rt_calloc(1,cnt*4);
            if(G_pDataBuf!=RT_NULL){
                log_printf("Allocated %d bytes memory.",cnt*4);
                cmd_free(RT_NULL,RT_NULL);
            }
        }
    }
    else if(argc==2){
        if (0 == rt_strcmp("free", argv[1]))
        {
            rt_free(G_pDataBuf);
            log_printf("free done");
            cmd_free(RT_NULL,RT_NULL);
        }
    }
    else
    {
        debug_test_usage();
        return;
    }
}
MSH_CMD_EXPORT(cmd_debug, cmd debug);
```
日志如下
```c
msh />cmd_debug malloc 1
1.[1970-01-01 08:00:36.087][debug_thread.c 986]:cnt:1
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     207364     185728        23212
2.[1970-01-01 08:00:36.109][debug_thread.c 992]:Allocated 4 bytes memory.
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     207364     185728        23040
msh />cmd_debug free    
3.[1970-01-01 08:00:48.268][debug_thread.c 1010]:free done
          pool size  max used size available size
-------- ---------- ------------- --------------
SRAM EX  1048576    48            1048528
heap     207364     185728        22952
msh />
```
我用的memheap，memtrace不一定适用，我测测看