Linux init/main.c 初始化中硬件中断向量初始化 trap_init()

void main(void)		/* This really IS void, no error here. */
{			/* The startup routine assumes (well, ...) this */
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
ROOT_DEV = ORIG_ROOT_DEV;
drive_info = DRIVE_INFO;
memory_end = (1<<20) + (EXT_MEM_K<<10);
memory_end &= 0xfffff000;
if (memory_end > 16*1024*1024)
memory_end = 16*1024*1024;
if (memory_end > 12*1024*1024)
buffer_memory_end = 4*1024*1024;
else if (memory_end > 6*1024*1024)
buffer_memory_end = 2*1024*1024;
else
buffer_memory_end = 1*1024*1024;
main_memory_start = buffer_memory_end;
#ifdef RAMDISK
main_memory_start += rd_init(main_memory_start, RAMDISK*1024);
#endif
mem_init(main_memory_start,memory_end);
trap_init();
blk_dev_init();
chr_dev_init();
tty_init();
time_init();
sched_init();
buffer_init(buffer_memory_end);
hd_init();
floppy_init();
sti();
move_to_user_mode();
if (!fork()) {		/* we count on this going ok */
init();
}

void trap_init(void)
{
int i;
//设置系统的硬件中断 中断位于kernel/asm.s 或 system_call.s
set_trap_gate(0,÷_error);//0中断，位于/kernel/asm.s 19行
set_trap_gate(1,&debug);
set_trap_gate(2,&nmi);
set_system_gate(3,&int3);	/* int3-5 can be called from all */
set_system_gate(4,&overflow);
set_system_gate(5,&bounds);
set_trap_gate(6,&invalid_op);
set_trap_gate(7,&device_not_available);
set_trap_gate(8,&double_fault);
set_trap_gate(9,&coprocessor_segment_overrun);
set_trap_gate(10,&invalid_TSS);
set_trap_gate(11,&segment_not_present);
set_trap_gate(12,&stack_segment);
set_trap_gate(13,&general_protection);
set_trap_gate(14,&page_fault);
set_trap_gate(15,&reserved);
set_trap_gate(16,&coprocessor_error);
for (i=17;i<48;i++)
set_trap_gate(i,&reserved);
set_trap_gate(45,&irq13);
outb_p(inb_p(0x21)&0xfb,0x21);
outb(inb_p(0xA1)&0xdf,0xA1);
set_trap_gate(39,¶llel_interrupt);
}

//n为中断向量号，addr中断程序的偏移地址
//&idt
对应中断号在中断描述符表中的偏移值
//中断描述符的类型是 14,特权级是 0。
#define set_trap_gate(n,addr) /
_set_gate(&idt
,15,0,addr)
//设置中断宏函数
//参数:gate_addr -描述符地址;type -描述符中类型域值;dpl -描述符特权层值;addr -偏移地址
// %0 - (由 dpl,type 组合成的类型标志字);%1 - (描述符低 4 字节地址);
// %2 - (描述符高 4 字节地址);%3 - edx(程序偏移地址 addr);%4 - eax(高字中含有段选择符)。
#define _set_gate(gate_addr,type,dpl,addr) /
__asm__ ("movw %%dx,%%ax/n/t" /
"movw %0,%%dx/n/t" /
"movl %%eax,%1/n/t" /
"movl %%edx,%2" /
: /
: "i" ((short) (0x8000+(dpl<<13)+(type<<8))), /
"o" (*((char *) (gate_addr))), /
"o" (*(4+(char *) (gate_addr))), /
"d" ((char *) (addr)),"a" (0x00080000))