/* link.lds */
 1 ENTRY(_start)                                                                                                      

 jiffies = jiffies_64;

 SECTIONS

 {

     . = 0x0;

     . = ALIGN();

     .text      :

     {

       test.o (.text)

       *(.text)

     }

     . = ALIGN();

     .rodata : { *(.rodata) }

     . = ALIGN();

     .data : { *(.data) }

     . = ALIGN();

     .got : { *(.got) }

     . = ALIGN();

     __bss_start = .;

     .bss : { *(.bss) }

     _end = .;

 }

#Makefile
 1 CROPROSS_COMPILER = arm-none-linux-gnueabi-

 LD := ${CROPROSS_COMPILER}ld

 AS := ${CROPROSS_COMPILER}as

 GCC := ${CROPROSS_COMPILER}gcc 

 mytest: test.o main.o

     ${LD} -T link.lds $^ -o $@

 test.o: test.S

     ${AS} $^ -o $@

 main.o : main.c

     ${GCC} -c $^ -o $@

 .PHONY: clean

 clean:

     @rm -f -r mytest test.o main.o 

#test.S
 1 .text

 .global _start

 _start:

     b 1f

 :

     mov r0, r0

 :

     mov r0, r0

 :

     mov r0, r0

 :

     b main  

 //main.c
 1 unsigned long long jiffies_64 = - * ;

 extern int jiffies;

 int main(void)

 {

     jiffies_64 += ;

     jiffies += ;

     return ;

 }

#反汇编，省略了一部分
 1  <_start>:

    :   b     <_start+0x4>

    :   nop

    :   nop

    c:   nop

   :   b    <main>

  <main>: 

   1c:   ldr r3, [pc, #]   ; 取jiffies_64地址

   :   ldm r3, {r1, r2}

   :   mov r3, #  ; 0x1   ; jiffies_64低位加1

   :   mov r4, #  ; 0x0   ; jiffies_64高位加0

   2c:   adds    r3, r3, r1

   :   adc r4, r4, r2

   :   ldr r2, [pc, #]   ; 取jiffies_64地址

   :   stm r2, {r3, r4}    ; 将jiffies_64 +  存入jiffies_64

   3c:   ldr r3, [pc, #]   ; 取jiffies地址

   :   ldr r3, [r3]

   :   add r2, r3, #      ; jiffies低位加3

   :   ldr r3, [pc, #]   ; 取jiffies地址

   4c:   str r2, [r3]        ; 将jiffies +  存入jiffies 

   :   .word   0x00000070  ; jiffies_64地址

   :   .word   0x00000070  ; jiffies地址

 Disassembly of section .data:

  <jiffies>:

   :   .word   0xfffedb08

   :   .word   0xffffffff