我正在比较CubeMX为STM32微控制器系列生成的链接描述文件。让我们看一下 STM32L476RG（NUCLEO-L476）和最新的 STM32F767ZI（NUCLEO-F767ZI）。
注意：链接描述文件是为arm-none-eabi-gcc编译器生成的。
最显着的区别在于链接描述文件SECTIONS部分中的对齐指令。这是 STM32L476RG 的.isr_vector部分：
.isr_vector :
{
. = ALIGN(8);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(8);
} >FLASH
这是 STM32F767ZI 的.isr_vector部分：
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >FLASH
几乎所有代码节中都有类似的区别。我做了一张桌子来比较：
STM32L476RG STM32F767ZI
+----------------+----------+ +----------------+----------+
| .isr_vector | ALIGN(8) | | .isr_vector | ALIGN(4) |
+----------------+----------+ +----------------+----------+
| .text | ALIGN(8) | | .text | ALIGN(4) |
+----------------+----------+ +----------------+----------+
| .rodata | ALIGN(8) | | .rodata | ALIGN(4) |
+----------------+----------+ +----------------+----------+
| .ARM.extab | ALIGN(8) | | .ARM.extab | / |
+----------------+----------+ +----------------+----------+
| .ARM | ALIGN(8) | | .ARM | / |
+----------------+----------+ +----------------+----------+
| .preinit_array | ALIGN(8) | | .preinit_array | / |
+----------------+----------+ +----------------+----------+
| .init_array | ALIGN(8) | | .init_array | / |
+----------------+----------+ +----------------+----------+
| .fini_array | ALIGN(8) | | .fini_array | / |
+----------------+----------+ +----------------+----------+
| .data | ALIGN(8) | | .data | ALIGN(4) |
+----------------+----------+ +----------------+----------+
| .bss | / | | .bss | / |
+----------------+----------+ +----------------+----------+
| ._user_heap_st | ALIGN(8) | | ._user_heap_st | ALIGN(8) |
+----------------+----------+ +----------------+----------+
| .ARM.attributes| / | | .ARM.attributes| / |
+----------------+----------+ +----------------+----------+
鉴于两个微控制器都具有32位体系结构，这些差异来自何处？
出于完整性考虑，我决定在此处添加完整的链接描述文件。您可以使用在线差异工具进行比较（https://www.diffchecker.com/）。以下是 STM32L476RG 微控制器的链接描述：
/*
*****************************************************************************
**
** File : LinkerScript.ld
**
** Abstract : Linker script for STM32L476RGTx Device with
** 1024KByte FLASH, 128KByte 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
**
** <h2><center>© COPYRIGHT(c) 2014 Ac6</center></h2>
**
** Redistribution and use in source and binary forms, with or without modification,
** are permitted provided that the following conditions are met:
** 1. Redistributions of source code must retain the above copyright notice,
** this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright notice,
** this list of conditions and the following disclaimer in the documentation
** and/or other materials provided with the distribution.
** 3. Neither the name of Ac6 nor the names of its contributors
** may be used to endorse or promote products derived from this software
** without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
** DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
** SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**
*****************************************************************************
*/
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = 0x20018000; /* 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 (xrw) : ORIGIN = 0x20000000, LENGTH = 96K
RAM2 (xrw) : ORIGIN = 0x10000000, LENGTH = 32K
FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 1024K
}
/* Define output sections */
SECTIONS
{
/* The startup code goes first into FLASH */
.isr_vector :
{
. = ALIGN(8);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(8);
} >FLASH
/* The program code and other data goes into FLASH */
.text :
{
. = ALIGN(8);
*(.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(8);
_etext = .; /* define a global symbols at end of code */
} >FLASH
/* Constant data goes into FLASH */
.rodata :
{
. = ALIGN(8);
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(8);
} >FLASH
.ARM.extab :
{
. = ALIGN(8);
*(.ARM.extab* .gnu.linkonce.armextab.*)
. = ALIGN(8);
} >FLASH
.ARM : {
. = ALIGN(8);
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
. = ALIGN(8);
} >FLASH
.preinit_array :
{
. = ALIGN(8);
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
. = ALIGN(8);
} >FLASH
.init_array :
{
. = ALIGN(8);
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
. = ALIGN(8);
} >FLASH
.fini_array :
{
. = ALIGN(8);
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
. = ALIGN(8);
} >FLASH
/* used by the startup to initialize data */
_sidata = LOADADDR(.data);
/* Initialized data sections goes into RAM, load LMA copy after code */
.data :
{
. = ALIGN(8);
_sdata = .; /* create a global symbol at data start */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
. = ALIGN(8);
_edata = .; /* define a global symbol at data end */
} >RAM AT> FLASH
/* 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) }
}
这是 STM32F767ZI 微控制器的链接描述文件：
/*
*****************************************************************************
**
** File : LinkerScript.ld
**
** Abstract : Linker script for STM32F767ZITx Device with
** 2048KByte FLASH, 512KByte 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
**
** <h2><center>© COPYRIGHT(c) 2014 Ac6</center></h2>
**
** Redistribution and use in source and binary forms, with or without modification,
** are permitted provided that the following conditions are met:
** 1. Redistributions of source code must retain the above copyright notice,
** this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright notice,
** this list of conditions and the following disclaimer in the documentation
** and/or other materials provided with the distribution.
** 3. Neither the name of Ac6 nor the names of its contributors
** may be used to endorse or promote products derived from this software
** without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
** DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
** SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**
*****************************************************************************
*/
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = 0x20080000; /* 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 (xrw) : ORIGIN = 0x20000000, LENGTH = 512K
FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 2048K
}
/* Define output sections */
SECTIONS
{
/* The startup code goes first into FLASH */
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >FLASH
/* The program code and other data goes into FLASH */
.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 */
} >FLASH
/* Constant data goes into FLASH */
.rodata :
{
. = ALIGN(4);
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(4);
} >FLASH
.ARM.extab : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
.ARM : {
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
} >FLASH
.preinit_array :
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
} >FLASH
.init_array :
{
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
} >FLASH
.fini_array :
{
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
} >FLASH
/* 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> FLASH
/* 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) }
}
答案 0 :(得分：1)
不要比较写得不好的链接描述文件。
其中大多数没有任何意义：
.isr_vectors必须按照SCB-> VTOR的要求进行512对齐。 大多数应用将向量表放在FLASH / RAM的开头-无论如何，此位置是512对齐的:)
其余的内容（除了中断进入机制可能要求将其对齐8个字节的堆栈-但默认情况下，在此系列的uC中（不需要重置内核配置寄存器的状态），这只是想像力谁写的。它们应对齐4个字节，以避免性能损失，因为这些micro允许未对齐的访问。
有人说总线的宽度为64（或128）位，这种对齐方式可能会对性能产生积极影响，但如果有的话，这是很小的。
如果您通过DMA访问内存位置，最好将其对齐以避免出现等待状态。
另一些Cotex内核不允许未对齐的访问。
PS 请记住，某些内存位置（在称为“设备内存类型”的文档中必须自然对齐-这意味着在32位系统上为4字节）