| 特性、思想 | 优点 | 缺点 |
| 分层结构 | 内核分多层,每层可单向调用更低一层提供的接口 | 1.便于调试和验证,自底向上逐层调试验证 | 1.仅可调用相邻低层,难以合理定义各层的边界 |
| 2.易扩充和易维护,各层之间调用接口清晰固定 | 2.效率低,不可跨层调用,系统调用执行时间长 |
| 模块化 | 将内核划分为多个模块,各模块之间相互协作。内核=主模块+可加载内核模块主模块:只负责核心功能,如进程调度、内存管理可加载内核模块:可以动态加载新模块到内核,而无需重新编译整个内核 | 1.模块间逻辑清晰易于维护,确定模块间接口后即可多模块同时开发 | 1.模块间的接口定义未必合理、实用 |
| 2.支持动态加载新的内核模块(如:安装设备驱动程序、安装新的文件系统模块到内核),增强OS适应性 |
| 2.模块间相互依赖,更难调试和验证 |
| 3.任何模块都可以直接调用其他模块,无需采用消息传递进行通信,效率高 |
| 宏内核(大内核) | 所有的系统功能都放在内核里(大内核结构的OS通常也采用了“模块化”的设计思想) | 1.性能高,内核内部各种功能都可以直接相互调用 | 1.内核庞大功能复杂,难以维护 |
| 2.大内核中某个功能模块出错,就可能导致整个系统崩溃 |
| 微内核 | 只把中断、原语、进程通信等最核心的功能放入内核。进程管理、文件管理、设备管理等功能以用户进程的形式运行在用户态 | 1.内核小功能少、易于维护,内核可靠性高 | 1.性能低,需要频繁的切换 用户态/核心态。用户态下的各功能模块不可以直接相互调用,只能通过内核的“消息传递”来间接通信 |
| 2.内核外的某个功能模块出错不会导致整个系统崩溃 | 2.用户态下的各功能模块不可以直接相互调用,只能通过内核的“消息传递”来间接通信 |
| 外核(exokernel) | 内核负责进程调度、进程通信等功能,外核负责为用户进程分配未经抽象的硬件资源,且由外核负责保证资源使用安全 | 1.外核可直接给用户进程分配“不虚拟、不抽象”的硬件资源,使用户进程可以更灵活的使用硬件资源 | 1.降低了系统的一致性 |
| 2.使系统变得更复杂 |
| 2.减少了虚拟硬件资源的“映射层”,提升效率 |
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}
]
},
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},
{
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}
]
},
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},
{
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}
]
},
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},
{
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"content": "需要的其他信息：中断/异常、错误码"
}
]
},
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},
{
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}
]
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]
},
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]
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"content": "1、输入输出中断I/O 传输结束或出错终端"
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]
},
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]
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]
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]
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"content": "要么是执行用户态中的代码——"
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]
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]
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},
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{
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"level": 1
},
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},
{
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"content": {
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"content": "九曲阑干"
}
],
"level": 1
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},
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}
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{
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"content": "将 CS 和 RIP 复位"
}
]
},
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},
{
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"content": {
"paragraph_content": [
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"content": "从 ROM（BIOS 程序）中读取 basic input/output system"
}
]
},
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],
[
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"content": "1.上电自检(POST，Power-on Self-Test) "
}
]
},
{
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"item_content": [
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"type": "text",
"content": "2.初始化硬件设备"
}
]
},
{
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"item_content": [
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"content": "3.搜索一个操作系统来启动。例如：硬盘、U盘、光盘"
}
]
},
{
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"item_content": [
{
"type": "text",
"content": "4.找到有效的设备后，把第一个扇区的内容拷贝到内存中起始地址是0x00007c00，然后跳转到这个地址处"
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]
}
]
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"content": "扇区，磁盘基本的读写单位，通常一个扇区大小是512个字节5B"
}
]
},
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},
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"content": "·硬盘的第一个扇区称为主引导记录（MBR，Master Boot Record）"
}
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},
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}
]
}
]
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},
{
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"content": {
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"content": "根据分区表的信息，寻找操作系统所在的具体分区，加载操作系统"
}
]
},
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},
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"content": {
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"content": "由于空间的限制，引导程序一般需要两步"
}
]
},
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]
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"content": "中断一般是异步的，由硬件随机产生，中断信号来自 CPU 外部。"
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"content": "于屏蔽状态时，处理器忽略该类中断信号。"
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},
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"content": "故障 "
}
]
},
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},
{
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}
]
},
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}
]
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"content": "对于单处理器系统，最简单的方法就是每个进程刚刚进入临界区后，立即屏蔽所有中断，在离开之前再打开中断。"
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]
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"content": "对于内核来说，当使用几条指令更新变量时，将中断屏蔽是很方便的"
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"content": "一种合适的通用互斥机制。"
}
]
},
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},
{
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"content": {
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"content": "用户获得中断的权限会有系统风险。一个进程禁止中断后，一直没有开放中断，会影响系统的正常运行。"
}
]
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"content": "中断/异常混淆的概念"
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],
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},
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}
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"level": 1
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"content": "·操作系统启动时，分配和初始化一个跳转表"
}
]
},
{
"item_type": "text",
"item_content": [
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"type": "text",
"content": "例如：缺页故障、缺页异常、缺页表示同一含义"
}
]
},
{
"item_type": "text",
"item_content": [
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"type": "text",
"content": "Intel手册中将中断分为内中断和外中断，内中断与异常表示同一含义"
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]
}
]
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"content": {
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"content": "当前 CPU 执行完指令，中断引脚电压变高说明有中断"
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]
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},
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"content": "然后去响应中断 "
}
]
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},
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"content": {
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}
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},
{
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"content": "I/O中断请求 "
}
]
},
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},
{
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"content": {
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"content": "不同中断信号"
}
]
},
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},
{
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"content": {
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"content": "中断向量表"
}
]
},
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},
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"content": "中断处理程序处于内核态"
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]
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},
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},
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"content": "缺页故障、缺页异常——地址不在内存中"
}
]
},
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},
{
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"content": {
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"content": "保护异常——地址不合法"
}
]
},
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},
{
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"content": {
"paragraph_content": [
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"content": "因此需要再次取一次故障指令"
}
]
},
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},
{
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