attribute有属性的含义，一般出现在代码中是用来定义“编译属性”的，当我们需要将C语言代码中的某个部分编译后链接到某个特定的段时，就需要在这个部分前面加上__attribute__((section(段名)))，例如在代码中使用了__attribute__ ((section(".isr_vector")))将实现的中断向量表数组设置为.isr_vector段的位置，等待链接器链接到.isr_vector段中。
因为中断向量表数组在los_hwi.c文件中，所以我们可以反汇编编译int_vector.c后生成的int_vector.o中间文件来一探究竟。
使用反汇编命令 arm-none-eabi-objdump -x -j.isr_vector。
-x选项用于显示数据段的全部信息，如果不加该选项则看不到完整的数据。-
-j.isr_vector选项用于反汇编指定的段，我们只关心.isr_vector段。
结果如下：
root@ubuntu:~/arm/rtos/02_cm3# arm-none-eabi-objdump -x -j.isr_vector int_vector.o int_vector.o: file format elf32-littlearm int_vector.o architecture: arm, flags 0x00000011: HAS_RELOC, HAS_SYMS start address 0x00000000 private flags = 5000000: [Version5 EABI] Sections: Idx Name Size VMA LMA File off Algn 3 .isr_vector 0000026c 00000000 00000000 00000050 2**2 CONTENTS, ALLOC, LOAD, RELOC, DATA SYMBOL TABLE: 00000000 l d .isr_vector 00000000 .isr_vector 00000000 g O .isr_vector 0000026c g_pfnVectors RELOCATION RECORDS FOR [.isr_vector]: OFFSET TYPE VALUE 00000004 R_ARM_ABS32 reset_handler 00000008 R_ARM_ABS32 NmiSR 0000000c R_ARM_ABS32 FaultISR 00000010 R_ARM_ABS32 IntDefaultHandler 00000014 R_ARM_ABS32 IntDefaultHandler 00000018 R_ARM_ABS32 IntDefaultHandler 0000002c R_ARM_ABS32 IntDefaultHandler 00000030 R_ARM_ABS32 IntDefaultHandler 00000038 R_ARM_ABS32 IntDefaultHandler 0000003c R_ARM_ABS32 systick_handler 00000040 R_ARM_ABS32 IntDefaultHandler 00000044 R_ARM_ABS32 IntDefaultHandler 00000048 R_ARM_ABS32 IntDefaultHandler 0000004c R_ARM_ABS32 IntDefaultHandler 00000050 R_ARM_ABS32 IntDefaultHandler 00000054 R_ARM_ABS32 IntDefaultHandler 00000058 R_ARM_ABS32 IntDefaultHandler 0000005c R_ARM_ABS32 IntDefaultHandler 00000060 R_ARM_ABS32 IntDefaultHandler 00000064 R_ARM_ABS32 IntDefaultHandler 00000068 R_ARM_ABS32 IntDefaultHandler 0000006c R_ARM_ABS32 IntDefaultHandler 00000070 R_ARM_ABS32 IntDefaultHandler 00000074 R_ARM_ABS32 IntDefaultHandler 00000078 R_ARM_ABS32 IntDefaultHandler 0000007c R_ARM_ABS32 IntDefaultHandler 00000080 R_ARM_ABS32 IntDefaultHandler 00000084 R_ARM_ABS32 IntDefaultHandler 00000088 R_ARM_ABS32 IntDefaultHandler 0000008c R_ARM_ABS32 IntDefaultHandler 00000090 R_ARM_ABS32 IntDefaultHandler 00000094 R_ARM_ABS32 IntDefaultHandler 00000098 R_ARM_ABS32 IntDefaultHandler 0000009c R_ARM_ABS32 IntDefaultHandler 000000a0 R_ARM_ABS32 IntDefaultHandler 000000a4 R_ARM_ABS32 IntDefaultHandler 000000a8 R_ARM_ABS32 IntDefaultHandler 000000ac R_ARM_ABS32 IntDefaultHandler 000000b0 R_ARM_ABS32 IntDefaultHandler 000000b4 R_ARM_ABS32 IntDefaultHandler 000000b8 R_ARM_ABS32 IntDefaultHandler 000000bc R_ARM_ABS32 IntDefaultHandler 000000c0 R_ARM_ABS32 IntDefaultHandler 000000c4 R_ARM_ABS32 IntDefaultHandler 000000c8 R_ARM_ABS32 IntDefaultHandler 000000cc R_ARM_ABS32 IntDefaultHandler 000000d0 R_ARM_ABS32 IntDefaultHandler 000000d4 R_ARM_ABS32 IntDefaultHandler 000000d8 R_ARM_ABS32 IntDefaultHandler 000000dc R_ARM_ABS32 IntDefaultHandler 000000e0 R_ARM_ABS32 IntDefaultHandler 000000e4 R_ARM_ABS32 IntDefaultHandler 000000e8 R_ARM_ABS32 IntDefaultHandler 000000ec R_ARM_ABS32 IntDefaultHandler 000000f0 R_ARM_ABS32 IntDefaultHandler 000000f4 R_ARM_ABS32 IntDefaultHandler 000000f8 R_ARM_ABS32 IntDefaultHandler 000000fc R_ARM_ABS32 IntDefaultHandler 00000100 R_ARM_ABS32 IntDefaultHandler 00000104 R_ARM_ABS32 IntDefaultHandler 00000108 R_ARM_ABS32 IntDefaultHandler 0000010c R_ARM_ABS32 IntDefaultHandler 00000110 R_ARM_ABS32 IntDefaultHandler 00000114 R_ARM_ABS32 IntDefaultHandler 00000118 R_ARM_ABS32 IntDefaultHandler 0000011c R_ARM_ABS32 IntDefaultHandler 00000120 R_ARM_ABS32 IntDefaultHandler 00000124 R_ARM_ABS32 IntDefaultHandler 00000128 R_ARM_ABS32 IntDefaultHandler 0000012c R_ARM_ABS32 IntDefaultHandler 00000130 R_ARM_ABS32 IntDefaultHandler 00000134 R_ARM_ABS32 IntDefaultHandler 00000138 R_ARM_ABS32 IntDefaultHandler 0000013c R_ARM_ABS32 IntDefaultHandler 00000150 R_ARM_ABS32 IntDefaultHandler 00000154 R_ARM_ABS32 IntDefaultHandler 00000158 R_ARM_ABS32 IntDefaultHandler 0000015c R_ARM_ABS32 IntDefaultHandler 000001b0 R_ARM_ABS32 IntDefaultHandler 000001b4 R_ARM_ABS32 IntDefaultHandler 000001b8 R_ARM_ABS32 IntDefaultHandler 000001bc R_ARM_ABS32 IntDefaultHandler 000001c0 R_ARM_ABS32 IntDefaultHandler 000001c4 R_ARM_ABS32 IntDefaultHandler 000001c8 R_ARM_ABS32 IntDefaultHandler 000001cc R_ARM_ABS32 IntDefaultHandler 000001d0 R_ARM_ABS32 IntDefaultHandler 000001d4 R_ARM_ABS32 IntDefaultHandler 000001d8 R_ARM_ABS32 IntDefaultHandler 000001dc R_ARM_ABS32 IntDefaultHandler 000001e0 R_ARM_ABS32 IntDefaultHandler 000001e4 R_ARM_ABS32 IntDefaultHandler 000001e8 R_ARM_ABS32 IntDefaultHandler 000001ec R_ARM_ABS32 IntDefaultHandler 000001f0 R_ARM_ABS32 IntDefaultHandler 000001f4 R_ARM_ABS32 IntDefaultHandler 000001f8 R_ARM_ABS32 IntDefaultHandler 000001fc R_ARM_ABS32 IntDefaultHandler 00000200 R_ARM_ABS32 IntDefaultHandler 00000204 R_ARM_ABS32 IntDefaultHandler 00000208 R_ARM_ABS32 IntDefaultHandler 00000210 R_ARM_ABS32 IntDefaultHandler 00000214 R_ARM_ABS32 IntDefaultHandler 00000218 R_ARM_ABS32 IntDefaultHandler 0000021c R_ARM_ABS32 IntDefaultHandler 00000220 R_ARM_ABS32 IntDefaultHandler 00000224 R_ARM_ABS32 IntDefaultHandler 00000228 R_ARM_ABS32 IntDefaultHandler 0000022c R_ARM_ABS32 IntDefaultHandler 00000230 R_ARM_ABS32 IntDefaultHandler 00000234 R_ARM_ABS32 IntDefaultHandler 00000238 R_ARM_ABS32 IntDefaultHandler 0000023c R_ARM_ABS32 IntDefaultHandler 00000240 R_ARM_ABS32 IntDefaultHandler 00000244 R_ARM_ABS32 IntDefaultHandler 00000248 R_ARM_ABS32 IntDefaultHandler 0000024c R_ARM_ABS32 IntDefaultHandler 00000250 R_ARM_ABS32 IntDefaultHandler 00000254 R_ARM_ABS32 IntDefaultHandler 00000258 R_ARM_ABS32 IntDefaultHandler 0000025c R_ARM_ABS32 IntDefaultHandler 00000260 R_ARM_ABS32 IntDefaultHandler 00000264 R_ARM_ABS32 IntDefaultHandler 00000268 R_ARM_ABS32 IntDefaultHandler
root@ubuntu:~/arm/rtos/02_cm3# cat int_vector.c #include "os_stdio.h" void ResetISR(void); static void NmiSR(void); static void FaultISR(void); static void IntDefaultHandler(void); extern unsigned long _etext; extern unsigned long _data; extern unsigned long _edata; extern unsigned long _stack_bottom; extern unsigned long _stack_top; extern void reset_handler(void); extern void systick_handler(void); __attribute__ ((section(".isr_vector")))void (*g_pfnVectors[])(void) = { 0x2000c000, // StackPtr, set in RestetISR ((unsigned int)reset_handler + 1), // The reset handler NmiSR, // The NMI handler FaultISR, // The hard fault handler IntDefaultHandler, // The MPU fault handler IntDefaultHandler, // The bus fault handler IntDefaultHandler, // The usage fault handler 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved IntDefaultHandler, // SVCall handler IntDefaultHandler, // Debug monitor handler 0, // Reserved IntDefaultHandler, // The PendSV handler systick_handler, // The SysTick handler IntDefaultHandler, // GPIO Port A IntDefaultHandler, // GPIO Port B IntDefaultHandler, // GPIO Port C IntDefaultHandler, // GPIO Port D IntDefaultHandler, // GPIO Port E IntDefaultHandler, // UART0 Rx and Tx IntDefaultHandler, // UART1 Rx and Tx IntDefaultHandler, // SSI0 Rx and Tx IntDefaultHandler, // I2C0 Master and Slave IntDefaultHandler, // PWM Fault IntDefaultHandler, // PWM Generator 0 IntDefaultHandler, // PWM Generator 1 IntDefaultHandler, // PWM Generator 2 IntDefaultHandler, // Quadrature Encoder 0 IntDefaultHandler, // ADC Sequence 0 IntDefaultHandler, // ADC Sequence 1 IntDefaultHandler, // ADC Sequence 2 IntDefaultHandler, // ADC Sequence 3 IntDefaultHandler, // Watchdog timer IntDefaultHandler, // Timer 0 subtimer A IntDefaultHandler, // Timer 0 subtimer B IntDefaultHandler, // Timer 1 subtimer A IntDefaultHandler, // Timer 1 subtimer B IntDefaultHandler, // Timer 2 subtimer A IntDefaultHandler, // Timer 2 subtimer B IntDefaultHandler, // Analog Comparator 0 IntDefaultHandler, // Analog Comparator 1 IntDefaultHandler, // Analog Comparator 2 IntDefaultHandler, // System Control (PLL, OSC, BO) IntDefaultHandler, // FLASH Control IntDefaultHandler, // GPIO Port F IntDefaultHandler, // GPIO Port G IntDefaultHandler, // GPIO Port H IntDefaultHandler, // UART2 Rx and Tx IntDefaultHandler, // SSI1 Rx and Tx IntDefaultHandler, // Timer 3 subtimer A IntDefaultHandler, // Timer 3 subtimer B IntDefaultHandler, // I2C1 Master and Slave IntDefaultHandler, // Quadrature Encoder 1 IntDefaultHandler, // CAN0 IntDefaultHandler, // CAN1 IntDefaultHandler, // CAN2 IntDefaultHandler, // Ethernet IntDefaultHandler, // Hibernate IntDefaultHandler, // USB0 IntDefaultHandler, // PWM Generator 3 IntDefaultHandler, // uDMA Software Transfer IntDefaultHandler, // uDMA Error IntDefaultHandler, // ADC1 Sequence 0 IntDefaultHandler, // ADC1 Sequence 1 IntDefaultHandler, // ADC1 Sequence 2 IntDefaultHandler, // ADC1 Sequence 3 IntDefaultHandler, // I2S0 IntDefaultHandler, // External Bus Interface 0 IntDefaultHandler, // GPIO Port J IntDefaultHandler, // GPIO Port K IntDefaultHandler, // GPIO Port L IntDefaultHandler, // SSI2 Rx and Tx IntDefaultHandler, // SSI3 Rx and Tx IntDefaultHandler, // UART3 Rx and Tx IntDefaultHandler, // UART4 Rx and Tx IntDefaultHandler, // UART5 Rx and Tx IntDefaultHandler, // UART6 Rx and Tx IntDefaultHandler, // UART7 Rx and Tx 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved IntDefaultHandler, // I2C2 Master and Slave IntDefaultHandler, // I2C3 Master and Slave IntDefaultHandler, // Timer 4 subtimer A IntDefaultHandler, // Timer 4 subtimer B 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved 0, // Reserved IntDefaultHandler, // Timer 5 subtimer A IntDefaultHandler, // Timer 5 subtimer B IntDefaultHandler, // Wide Timer 0 subtimer A IntDefaultHandler, // Wide Timer 0 subtimer B IntDefaultHandler, // Wide Timer 1 subtimer A IntDefaultHandler, // Wide Timer 1 subtimer B IntDefaultHandler, // Wide Timer 2 subtimer A IntDefaultHandler, // Wide Timer 2 subtimer B IntDefaultHandler, // Wide Timer 3 subtimer A IntDefaultHandler, // Wide Timer 3 subtimer B IntDefaultHandler, // Wide Timer 4 subtimer A IntDefaultHandler, // Wide Timer 4 subtimer B IntDefaultHandler, // Wide Timer 5 subtimer A IntDefaultHandler, // Wide Timer 5 subtimer B IntDefaultHandler, // FPU IntDefaultHandler, // PECI 0 IntDefaultHandler, // LPC 0 IntDefaultHandler, // I2C4 Master and Slave IntDefaultHandler, // I2C5 Master and Slave IntDefaultHandler, // GPIO Port M IntDefaultHandler, // GPIO Port N IntDefaultHandler, // Quadrature Encoder 2 IntDefaultHandler, // Fan 0 0, // Reserved IntDefaultHandler, // GPIO Port P (Summary or P0) IntDefaultHandler, // GPIO Port P1 IntDefaultHandler, // GPIO Port P2 IntDefaultHandler, // GPIO Port P3 IntDefaultHandler, // GPIO Port P4 IntDefaultHandler, // GPIO Port P5 IntDefaultHandler, // GPIO Port P6 IntDefaultHandler, // GPIO Port P7 IntDefaultHandler, // GPIO Port Q (Summary or Q0) IntDefaultHandler, // GPIO Port Q1 IntDefaultHandler, // GPIO Port Q2 IntDefaultHandler, // GPIO Port Q3 IntDefaultHandler, // GPIO Port Q4 IntDefaultHandler, // GPIO Port Q5 IntDefaultHandler, // GPIO Port Q6 IntDefaultHandler, // GPIO Port Q7 IntDefaultHandler, // GPIO Port R IntDefaultHandler, // GPIO Port S IntDefaultHandler, // PWM 1 Generator 0 IntDefaultHandler, // PWM 1 Generator 1 IntDefaultHandler, // PWM 1 Generator 2 IntDefaultHandler, // PWM 1 Generator 3 IntDefaultHandler // PWM 1 Fault };
root@ubuntu:~/arm/rtos/02_cm3# objdump -s -j .text rtos.elf rtos.elf: file format elf32-littlearm Contents of section .text: 0000 00c00020 b90c0000 6d020000 73020000 ... ....m...s... 0010 79020000 79020000 79020000 00000000 y...y...y....... 0020 00000000 00000000 00000000 79020000 ............y... 0030 79020000 00000000 79020000 c1020000 y.......y....... 0040 79020000 79020000 79020000 79020000 y...y...y...y... 0050 79020000 79020000 79020000 79020000 y...y...y...y... 0060 79020000 79020000 79020000 79020000 y...y...y...y... 0070 79020000 79020000 79020000 79020000 y...y...y...y... 0080 79020000 79020000 79020000 79020000 y...y...y...y... 0090 79020000 79020000 79020000 79020000 y...y...y...y... 00a0 79020000 79020000 79020000 79020000 y...y...y...y... 00b0 79020000 79020000 79020000 79020000 y...y...y...y... 00c0 79020000 79020000 79020000 79020000 y...y...y...y... 00d0 79020000 79020000 79020000 79020000 y...y...y...y... 00e0 79020000 79020000 79020000 79020000 y...y...y...y... 00f0 79020000 79020000 79020000 79020000 y...y...y...y... 0100 79020000 79020000 79020000 79020000 y...y...y...y... 0110 79020000 79020000 79020000 79020000 y...y...y...y... 0120 79020000 79020000 79020000 79020000 y...y...y...y... 0130 79020000 79020000 79020000 79020000 y...y...y...y... 0140 00000000 00000000 00000000 00000000 ................ 0150 79020000 79020000 79020000 79020000 y...y...y...y...
root@ubuntu:~/arm/rtos/02_cm3# arm-none-eabi-objdump -x -j.isr_vector rtos.elf rtos.elf: file format elf32-littlearm rtos.elf architecture: arm, flags 0x00000112: EXEC_P, HAS_SYMS, D_PAGED start address 0x00000000 Program Header: LOAD off 0x00010000 vaddr 0x00000000 paddr 0x00000000 align 2**16 filesz 0x00000d80 memsz 0x00000d80 flags r-x private flags = 5000200: [Version5 EABI] [soft-float ABI] Sections: Idx Name Size VMA LMA File off Algn SYMBOL TABLE: arm-none-eabi-objdump: section '.isr_vector' mentioned in a -j option, but not found in any input file root@ubuntu:~/arm/rtos/02_cm3# ls cm3.c cm3.o cm3_s.o cm3_s.s include int_vector.c int_vector.o main.c main.o Makefile os_stdio.c os_stdio.o rtos.bin rtos.dis rtos.elf rtos.ld root@ubuntu:~/arm/rtos/02_cm3# arm-none-eabi-objdump -x -j.isr_vector cm3.o cm3.o: file format elf32-littlearm cm3.o architecture: arm, flags 0x00000011: HAS_RELOC, HAS_SYMS start address 0x00000000 private flags = 5000000: [Version5 EABI] Sections: Idx Name Size VMA LMA File off Algn SYMBOL TABLE: arm-none-eabi-objdump: section '.isr_vector' mentioned in a -j option, but not found in any input file root@ubuntu:~/arm/rtos/02_cm3# arm-none-eabi-objdump -x -j.isr_vector cm3 cm3.c cm3.o cm3_s.o cm3_s.s root@ubuntu:~/arm/rtos/02_cm3# arm-none-eabi-objdump -x -j.isr_vector cm3_s.o cm3_s.o: file format elf32-littlearm cm3_s.o architecture: arm, flags 0x00000011: HAS_RELOC, HAS_SYMS start address 0x00000000 private flags = 5000000: [Version5 EABI] Sections: Idx Name Size VMA LMA File off Algn SYMBOL TABLE: arm-none-eabi-objdump: section '.isr_vector' mentioned in a -j option, but not found in any input file root@ubuntu:~/arm/rtos/02_cm3#