why my vaiable not following the code in gdb stm32 project - c

Question

my code here:
void _init(void) {return;}
int main(void)
{
/* STM32F2xx HAL library initialization:
- Configure the Flash prefetch, instruction and Data caches
- Configure the Systick to generate an interrupt each 1 msec
- Set NVIC Group Priority to 4
- Global MSP (MCU Support Package) initialization
*/
HAL_Init();
/* Configure the system clock to 64 MHz */
SystemClock_Config();
/* Enable CRC clock */
__CRC_CLK_ENABLE();
Example_Status = 1;
Example_Status = 2;
Example_Status = 3;
.....
and my gdb on my stm32 using stlink-texane are as follow:
(gdb) s
main () at main.c:74
74 __CRC_CLK_ENABLE();
(gdb) s
77 Example_Status = 3;
(gdb) p Example_status
No symbol "Example_status" in current context.
(gdb) p Example_Status
$1 = 139640994
(gdb) n
74 __CRC_CLK_ENABLE();
(gdb) n
77 Example_Status = 3;
(gdb) n
183 Example_Status = ExampleECCKeyGenSignVerif();
(gdb) p Example_Status
$2 = 139640994
i am wondering why the Example_Status outcome not = 3 ?
and the storage of the variable are
arm-none-eabi-objdump --syms main.o | grep Example_Status
00000000 l d .bss.Example_Status 00000000 .bss.Example_Status
00000000 g O .bss.Example_Status 00000004 Example_Status
and my linker file are here:
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = 0x20010000; /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x000;; /* required amount of heap */
_Min_Stack_Size = 0x000;; /* required amount of stack */
/* Specify the memory areas */
MEMORY
{
FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 128K
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 64K
}
/* 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) }
}
This is my first linux project, i would appreicate if someone can help~
thanks
Edited for adding "disassemble /m"
75 Example_Status = 1;
0x080002ac <+24>: and.w r3, r3, #33554432 ; 0x2000000
0x080002b0 <+28>: cmp r3, #0
---Type <return> to continue, or q <return> to quit---
76 Example_Status = 2;
0x080002b2 <+30>: beq.n 0x80002a8 <main+20>
0x080002b4 <+32>: ldr r3, [pc, #60] ; (0x80002f4 <main+96>)
0x080002b6 <+34>: movw r2, #1795 ; 0x703
77 Example_Status = 3;
0x080002b8 <+36>: strb r3, [r0, #8]
0x080002ba <+38>: str r2, [r3, #0]
0x080002bc <+40>: ldr r2, [pc, #44] ; (0x80002ec <main+88>)
//
(gdb) n
75 Example_Status = 1;
(gdb) n
76 Example_Status = 2;
(gdb) p Example_Status
$1 = 140166176
(gdb) s

Answer 1

When compiling, and you want reliable debugging, do not compile with optimization-level higher than 0:
gcc -O0 mycode.c -o mycode.o -c