操作系统学习笔记(27)--初始化中断

设置中断。

 

中断的常用设置是8259A，通过级联支持15个中断，通过发送ICW和OCW设置进行响应。 

 

1 该过程是初始化系统的中断向量表，一般是256个入口。

2 然后需要给出基地址，该地址通过ldt装入寄存器。

 

3 在每个入口处，对应中断处理函数，该入口存放函数的入口地址。

 

4 开中断开始响应中断处理。

 

在中断处理过程中需要内核的处理权限等。

中断处理有中断门概念，相当于中断处理入口。

 

struct Interrupt_State { /* * The register contents at the time of the exception. * We save these explicitly. */ uint_t gs; uint_t fs; uint_t es; uint_t ds; uint_t ebp; uint_t edi; uint_t esi; uint_t edx; uint_t ecx; uint_t ebx; uint_t eax; /* * We explicitly push the interrupt number. * This makes it easy for the handler function to determine * which interrupt occurred. */ uint_t intNum; /* * This may be pushed by the processor; if not, we push * a dummy error code, so the stack layout is the same * for every type of interrupt. */ uint_t errorCode; /* These are always pushed on the stack by the processor. */ uint_t eip; uint_t cs; uint_t eflags;

 

struct Interrupt_Gate { ushort_t offsetLow; ushort_t segmentSelector; unsigned reserved : 5; unsigned signature : 8; unsigned dpl : 2; unsigned present : 1; ushort_t offsetHigh;};

上述中断门对应8个字节。unsigned short是2个字节 unsigned一共是2个节。