【发布时间】：2021-04-13 12:20:12
【问题描述】：
问题是当我这样定义数组时：
float Data_Set_X[15000];
float Data_Set_Y[15000];
float Data_Set_Z[15000];
我收到 RAM 溢出错误：.bss will not fit in region RAM Timer-Blink-Test_CM7 C/C++ 问题
当我初始化至少一个或三个数组时，错误将消失。
float Data_Set_X[15000]={0};
float Data_Set_Y[15000];
float Data_Set_Z[15000];
我的变量是全局的。
在链接描述文件中写道：
/* Specify the memory areas */
MEMORY
{
RAM_EXEC (rx) : ORIGIN = 0x24000000, LENGTH = 256K
RAM (xrw) : ORIGIN = 0x24040000, LENGTH = 256K
}
/* The startup code goes first into RAM_EXEC */
/* The program code and other data goes into RAM_EXEC */
/* Constant data goes into RAM_EXEC */
/* Initialized data sections goes into RAM, load LMA copy after code */
根据链接描述文件，/* Uninitialized data section */ 有一个单独的 RAM 部分。
RAM 大小为 1MB，用户可以访问大约 800KB。 MCU有双核，我使用M7 Core。如链接器脚本文件中所述，该内核可以访问 512KB RAM 区域。这三个数组的总大小是180KB
这是我的微控制器的链接器脚本文件
/*
******************************************************************************
**
** File : LinkerScript.ld
**
**
** Abstract : Linker script for STM32H7 series
** 256Kbytes RAM_EXEC and 256Kbytes RAM
**
** Set heap size, stack size and stack location according
** to application requirements.
**
** Set memory bank area and size if external memory is used.
**
** Target : STMicroelectronics STM32
**
** Distribution: The file is distributed as is, without any warranty
** of any kind.
**
*****************************************************************************
** @attention
**
** Copyright (c) 2019 STMicroelectronics.
** All rights reserved.
**
** This software component is licensed by ST under BSD 3-Clause license,
** the "License"; You may not use this file except in compliance with the
** License. You may obtain a copy of the License at:
** opensource.org/licenses/BSD-3-Clause
**
****************************************************************************
*/
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = 0x24080000; /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x200 ; /* required amount of heap */
_Min_Stack_Size = 0x400 ; /* required amount of stack */
/* Specify the memory areas */
MEMORY
{
RAM_EXEC (rx) : ORIGIN = 0x24000000, LENGTH = 256K
RAM (xrw) : ORIGIN = 0x24040000, LENGTH = 256K
}
/* Define output sections */
SECTIONS
{
/* The startup code goes first into RAM_EXEC */
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >RAM_EXEC
/* The program code and other data goes into RAM_EXEC */
.text :
{
. = ALIGN(4);
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.glue_7) /* glue arm to thumb code */
*(.glue_7t) /* glue thumb to arm code */
*(.eh_frame)
KEEP (*(.init))
KEEP (*(.fini))
. = ALIGN(4);
_etext = .; /* define a global symbols at end of code */
} >RAM_EXEC
/* Constant data goes into RAM_EXEC */
.rodata :
{
. = ALIGN(4);
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(4);
} >RAM_EXEC
.ARM.extab : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >RAM_EXEC
.ARM : {
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
} >RAM_EXEC
.preinit_array :
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
} >RAM_EXEC
.init_array :
{
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
} >RAM_EXEC
.fini_array :
{
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
} >RAM_EXEC
/* used by the startup to initialize data */
_sidata = LOADADDR(.data);
/* Initialized data sections goes into RAM, load LMA copy after code */
.data :
{
. = ALIGN(4);
_sdata = .; /* create a global symbol at data start */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
. = ALIGN(4);
_edata = .; /* define a global symbol at data end */
} >RAM AT> RAM_EXEC
/* Uninitialized data section */
. = ALIGN(4);
.bss :
{
/* This is used by the startup in order to initialize the .bss secion */
_sbss = .; /* define a global symbol at bss start */
__bss_start__ = _sbss;
*(.bss)
*(.bss*)
*(COMMON)
. = ALIGN(4);
_ebss = .; /* define a global symbol at bss end */
__bss_end__ = _ebss;
} >RAM
/* User_heap_stack section, used to check that there is enough RAM left */
._user_heap_stack :
{
. = ALIGN(8);
PROVIDE ( end = . );
PROVIDE ( _end = . );
. = . + _Min_Heap_Size;
. = . + _Min_Stack_Size;
. = ALIGN(8);
} >RAM
/* Remove information from the standard libraries */
/DISCARD/ :
{
libc.a ( * )
libm.a ( * )
libgcc.a ( * )
}
.ARM.attributes 0 : { *(.ARM.attributes) }
}
谢谢！
【问题讨论】：
-
float Data_Set_X[15000]={0};在全局范围内定义时等同于float Data_Set_X[15000];。所以这里有些不对劲。请发帖minimal reproducible example。 -
@EugeneSh。较旧的 gcc 版本将零初始化变量放入 .data 部分。
-
@P__JsupportswomeninPoland 真的吗？你知道他们什么时候停下来的吗？
-
@EugeneSh。前一段时间。不记得版本。我的意思是显式初始化为零，例如
int x = 0; -
@EugeneSh。我也经历过这个。 ，arm-gcc 在早期的 4.x 范围内（可能是 4.1？）。
char x[10000] = { 0 };会将二进制文件的大小增加 10K 。我的代码库还必须使用另一个编译器构建，它不会对未初始化的静态变量进行零初始化，所以我最终不得不定义一个宏ZERO_INITIALIZED，它在 gcc 上扩展为空白，在另一个平台上扩展为= { 0 }！