linux情景分析之中断有感

     

之前一直被x86体系的各种门锁困扰，比如中断门，陷阱门等等。不知道这些和irq_desc的关系。

 linux初始化过程中，会完成终端机制的初始化，中断向量表IDT的初始化尤为重要。主要是调用trap_init和init_IRQ两个函数。

其中trap_init主要是对一些系统保留的中断向量的初始化，主要是中断向量表前20个陷阱门，都是保留给异常处理的。

void __init trap_init(void)
{
	int i;


#ifdef CONFIG_EISA
	void __iomem *p = early_ioremap(0x0FFFD9, 4);


	if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
		EISA_bus = 1;
	early_iounmap(p, 4);
#endif


	set_intr_gate(0, ÷_error);
	set_intr_gate_ist(2, &nmi, NMI_STACK);
	/* int4 can be called from all */
	set_system_intr_gate(4, &overflow);
	set_intr_gate(5, &bounds);
	set_intr_gate(6, &invalid_op);
	set_intr_gate(7, &device_not_available);
#ifdef CONFIG_X86_32
	set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
#else
	set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
#endif
	set_intr_gate(9, &coprocessor_segment_overrun);
	set_intr_gate(10, &invalid_TSS);
	set_intr_gate(11, &segment_not_present);
	set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
	set_intr_gate(13, &general_protection);
	set_intr_gate(15, &spurious_interrupt_bug);
	set_intr_gate(16, &coprocessor_error);
	set_intr_gate(17, &alignment_check);
#ifdef CONFIG_X86_MCE
	set_intr_gate_ist(18, &machine_check, MCE_STACK);
#endif
	set_intr_gate(19, &simd_coprocessor_error);


	/* Reserve all the builtin and the syscall vector: */
	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
		set_bit(i, used_vectors);


#ifdef CONFIG_IA32_EMULATION
	set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
	set_bit(IA32_SYSCALL_VECTOR, used_vectors);
#endif


#ifdef CONFIG_X86_32
	set_system_trap_gate(SYSCALL_VECTOR, &system_call);
	set_bit(SYSCALL_VECTOR, used_vectors);
#endif


	/*
	 * Should be a barrier for any external CPU state:
	 */
	cpu_init();


	x86_init.irqs.trap_init();