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

最新推荐文章于 2023-12-10 23:37:56 发布

最新推荐文章于 2023-12-10 23:37:56 发布 · 179 阅读

本文详细介绍了Linux内核的启动过程，包括关键的内存分配、设备初始化及中断处理机制。特别关注了/init/main.c文件中的核心初始化流程，以及/kernel/traps.c中的中断向量表设置。

/init/main.c部分代码

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(); }

trap_init()函数位置 /kernel/traps.c

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); }

set_trap_gate()函数位于/include/asm/system.h

//n为中断向量号，addr中断程序的偏移地址 //&idt[n]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[n],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))