30 内存使用如何查看 free命令查看的内存大小是否正确

发布于 2021-06-25 17:06:54 浏览：2716 订阅该版

STM32F427VGTx 
![image.png](https://oss-club.rt-thread.org/uploads/20210625/5cbc16e98de2da1f2507a1ce9c2e798c.png.webp)
 拥有sram 192Kb ccm 64KB 
 查看link.lds文件中sram = 192k 也没有错
 ```
 MEMORY
{
    ROM (rx) : ORIGIN =0x08020000,LENGTH =1024k
    RAM (rw) : ORIGIN =0x20000000,LENGTH =192k
    /*CCRAM (rw) : ORIGIN =0x10000000,LENGTH =64k*/
}
 ```
 查看board.h
 ```
#define ROM_START              ((uint32_t)0x08000000)
#define ROM_SIZE               (1024 * 1024)
#define ROM_END                ((uint32_t)(ROM_START + ROM_SIZE))

#define RAM_START              (0x20000000)
#define RAM_SIZE               (192 * 1024)
#define RAM_END                (RAM_START + RAM_SIZE)
 ```
 这里也是192kb 
在shell中使用free 命令如下
 total memory:128672
 used memory:48000
 maximun allocated memory:53680 
 有点奇怪的是这里的内存之后125KB 左右。。。
 请问下这个是什么原因呢？ 
 如何查看自己内存大小呢？
  
 然后我加入CCM 支持 更改lds
 
  ```
 MEMORY
{
    ROM (rx) : ORIGIN =0x08020000,LENGTH =1024k
    RAM (rw) : ORIGIN =0x20000000,LENGTH =192k
    /*CCRAM (rw) : ORIGIN =0x10000000,LENGTH =64k*/
}
 ```
 加入ccm段
 ```
     _sidata = LOADADDR(.data);
    /* .data : AT (_sidata) */
    .data :
    {
        . = 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  */
    } >RAM AT>ROM

_siccmram = LOADADDR(.ccmram);
    .ccmram :
    {
    . = ALIGN(4);
    _sccmram = .; /* create a global symbol at ccmram start */
    *(.ccmram)
    *(.ccmram*)
    . = ALIGN(4);

_eccmram = .; /* create a global symbol at ccmram end */
    /* } >CCMRAM  */
    } >CCMRAM AT>ROM
 ```
 如何查看我这个CCM 加入成功了呢？