操作系统虚拟机小论文

课程设计课程设计名称：计算机操作系统专业班级：计算机科学与技术学生姓名：学号：指导教师：课程设计时间：操作系统专业课程设计任务书说明：本表由指导教师填写，由教研室主任审核后下达给选题学生，装订在设计（论文）首页目录一、设计目的为了掌握Linux环境下常用编译工具如gcc/g++/nasm及开源虚拟机bochs 的下载、安装、使用，掌握x86架构下分页式存储管理系统的基本原理,设计一个请求分页式虚拟存储系统。

掌握Linux系统下程序的编写及运行等方面展开实验。

二、设计要求2.1要求熟练掌握sudo apt-get install的用法。

2.2要求能够掌握分页存储管理系统的基本原理。

2.3要求学会在Linux系统下编写程序、执行程序。

三、设计容3.1运行环境3.1.1虚拟机系统下3.1.2使用Ubuntu下提供的apt-get软件包安装工具安装vim、 g++ 、nasm 、bochs等3.2 2.详细设计1）回顾虚拟页式存储系统：作业分页，存分块，只有当进程要使请认真阅读readme.txt文件，弄清楚各个文件的作用2）用其虚拟存时,其对应的数据才装入物理存。

3）完成frame_pool.H 、frame_pool.C 、page_table.C三个文件，其中page_table.H已经提供，我们需要添加page_table.C,自己设计并实现这些函数。

4）在frame_pool.H定义所需要的数据结构，在frame_pool.C完成这些函数。

添加代码如下所示：class FramePool {private: unsigned long base_frame_no; unsigned long nframes;unsigned long info_frame_no; unsigned char* free_frames;public:static const unsigned char USED -1;static const unsigned char UNUSED -0;static const unsigned int FRAME_SIZE -4096;public:FramePool(unsigned long _base_frame_no,unsigned long _nframes,unsigned long _info_frame_no);5）建立Frame_pool.C文件系统中使用位示图bitmap标识页面是否使用，start_frame表示第一个页面的起始地址（如系统存池从2M开始），pool_size表示在用户池中页框的总数（如系统存池的页框从2M~4M，因此共有（4M-2M）/4KB=512个页框）。

初始化用户池中位示图的容Frame_pool::frame_pool（）初始化bitmap记录系统中所有物理块是否可用，如果可用设置为0，否则为1。

Frame_pool::get_frame（）通过该方法去查询bitmap，查找可用物理块号。

FramePool::mark_inaccessible( )方法将bitmap中对应位置置1。

FramePool::release_frame（）方法将bitmap中对应位置置0。

设计一个私有函数set_frame_flag ，来设置某一个字节的某个bit为0或则为1。

6）打开page_table.H页表如下图所示：其中，页面大小为4K，即可用12位表示页地址，各个位含义如上图页表所示，其余20位表示页号，即1M。

7）创建一个文件：page_table.CPageTable::init_paging()给私有变量传递参数。

PageTable::PageTable()构造函数。

当bochs启动时，start.asm首先被读入到软盘镜像文件中，并将kernel.C 放入到存1MB-2MB空间，然后启动CPU运行，操作系统开始启动。

#include "page_table.H"#include "exceptions.H"#include "frame_pool.H"#include "paging_low.H"FramePool* PageTable::kernel_mem_pool =NULL;FramePool* PageTable::process_mem_pool =NULL;unsigned long PageTable::shares_size;PageTable*PageTable::current_page_table;void PageTable::init_paging(FramePool* _kernel_mem_pool,FramePool* _process_mem_pool,const unsigned long _shared_size){kernel_mem_pool =_kernel_mem_pool;process_mem_pool =_process_mem_pool;shared_size =_shared_size;}PageTable::PageTable(){unsigned long phys_address =0;page_directory =(unsigned long*) (kernel_mem_pool->get_frame()* PAGE_SIZE);unsigned long* page_table=(unsigned long*)(kernel_mem_pool->get_frame() *PAGE_SIZE);for(unsigned int i=0;i<ENTRIES_PER_PAGE;i++) {page_table[i]=phys_address|3phys_address+=PAGE_SIZE;}page_directory[0]=(unsigned long) page_table |3;for(unsigned int i=1;i<ENTRIES_PER_PAGE;i++){ page_directory[i]=0|2;}void PageTable::enable_paging()writE_cr3((unsigned long )(current_page_table->page_directory));write_cr0(read_cr0()|0x80000000);}void PageTable::handle_fault(REGS *_r){unsigned int page_fault_addr=read_cr2()unsigned long* page_table;Console::putui(page_fault_addr);Console::puts("\n");unsigned int page_dir_entry+page_fault_addr >>22;unsigned long page_table_addr =current_page->directory[page_dir_entry];if ((page_fault_addr & 0x01)==0){unsigned long new_page_table_addr=kernel_mem_pool ->get_frame() *PAGE_SIZE;page_table=(unsigned long*)(new_page_table_addr);current_page_table->page_directory[page_dir_entry]=(unsigned long) new_page_table_addr|3;for(unsigned int i=0;i<ENTRIES_PER_PAGE;i++){page_table[i]=0x00;}} else{page_table=(unsigned long*)(page_table_addr &0xFFFF000);unsigned long free_frame_no=process_mem_pool->frame();page_table[page_tab_entry]=(free_frame_no*PAGE_SIZE)|7;}代码如下：#include "page_table.H"#include "exceptions.H"#include "frame_pool.H"#include "paging_low.H"FranePool* PageTable::kernel_mem_pool = NULL;FramePool* PageTable::process_mem_pool = NULL;unsigned long PageTable::shared_size;PageTable* PageTable::curent_page_table;void PageTable::init_paging(FarmePool* _kernel_mem_pool,FramePool* _process_mem_pool,const unsigned long _shared_size) {kernel_mem_pool = _kernel_mem_pool;process_mem_pool = _process_mem_pool;shared_size = _shared_size;}PageTable::PageTable(){unsigned long phys_address = 0;page_directory = (unsigned long *)(kernel_mem_pool->get_frame() * PAGE_SIZE);unsigned long * page_table = (unsigned long *)(kernel_mem_pool->get_frame() * PAGE_SIZE);for(unsigned int i = 0; i<ENTRIES_PER_PAGE;i++){page_table[i] = phys_adress | 3;phys_adress += PAGE_SIZE;}page_directory[0] = (unsigned long) page_table | 3;for(unsigned int i = 1;i < ENTRIES_PER_PAGE;i++){page_directory[i] = 0 | 2;}}void PageTable::enable_paging(){write_cr3 ((unsigned long ) (current_page_table_>page_directory));write_cr0(read_cr0() | 0x80000000);}void PageTable::handle_fault(REGS * _r)(unsigned int page_fault_addr = read_cr2();unsigned long* page_table;Console::putui(page_fault_addr);Console::puts("\n");unsigned int page_dir-entry = page_fault_addr >>22;unsigned int page_dir-entry = (page_fault_addr & (0x03FF << 12)) >> 12;unsigned long page_table_addr = current_page_table->page_directory[page_dir_entry];if ((page_fault_addr & 0x01 == 0){unsigned long new_page_table_addr = kernel_men_pool -> get_frame() * PAGE_SIZE;page_table = (unsigned long*) (new_page_table_addr);current_page_table->page_directory[page_dir_entry] = (unsigned long new_page_table_addr | 3;for(unsiqned int i =0;i<ENTRIKS_PER_PAGE:i++){page_table[i]=0x00;}}else{//Page table has been present, but the entry in page table is not present//get page table address from page_table_addrpage_table=(unsigned long*) {page_table_addr&0xFFFFF000);}//find a free framo from process memory pool and give it to page table entryunsigned long free_framo_no=process_mem_pool->get_framo();//attributo set to; user level,read/write, present(111 in binary)page_table(page_tab_entry)=(free_framo_no*PAGE_SIZE)1 7; #include "frame_pool.H"#define MB * (0x1 << 20)#define kB * (0x1 << 20)Framepool::Framepool(unsigned long _base_frame_no,unsigned long _nframe,unsigned long _info_frame_no){base_frame_no =_base_frame_no;nframes =_nframes;info_frame_no =_info_frame_no;if (info_frame_no == 0){info_frame_no - (2MB)/FRAME_SIZE;}free_frames =(unsigned char*)(info_frame_no * FRAME_SIZE); unsigned long total_bitmap_bytes = (nframes + 7) /8;for( unsigned long i = 0;i<total_bitmap_bytes; i++){free_frames[ i ] =0x00;}set_frame_flag(info_frame_no,USED);}/////////////////////////////////unsigned long Framepool::get_frame(){unsigned long which_byte_free;unsigned char val;unsigned long total_bitmap_bytes = (nframes + 7) /8;for(which_byte_free = 0;which_byte_free<total_bitmap_bytes;which_byte_free++) {val = *(free_frame + which_byte_free);if(val !=0xFF)break;}if(val == 0xFF)return 0;char bit = 0;while(1){if ((va;&(USED<<BIT)) ==0)break;bit++;}unsigned long abs_free_frame_add =base_frame_no + which_byte_free *8 + bit;set_frame_flag( abs_free_frame_add ,USED);return abs_free_frame_add;}void Framepool::mark_inaccessible(unsigned long _base_frame_no, unsigned long _nframe,){for(unsigned long i = 0;i < _nframes; i++){set_frame_flag(_base_frame_no + i,USED);}}void Framepool::release_frame( unsigned long _frame_no){set_frame_flag(_frame_no,UNUSED);}inline void Framepool::set_frame_flag(unsigned long _frame_no, unsigned char ifused) {_frame_on -= base_frame_on;int bit_counter = _frame_on%8;unsigned char mask = 0;if(ifused ==USED){mask=(0x01 << bit_counter);*(free_frames + _frame_no /8) |=mask; }else {mask=(~(0x01 << bit_counter));*(free_frames + _frame_no /8) &=mask; }}#include "page_table.H"#include "exceptions.H"#include "frame_pool.H"#include "paging_low.H"FranePool* PageTable::kernel_mem_pool = NULL; FramePool* PageTable::process_mem_pool = NULL; unsigned long PageTable::shared_size; PageTable* PageTable::curent_page_table;void PageTable::init_paging(FarmePool* _kernel_mem_pool,FramePool* _process_mem_pool,const unsigned long _shared_size){kernel_mem_pool = _kernel_mem_pool;process_mem_pool = _process_mem_pool;shared_size = _shared_size;}PageTable::PageTable(){unsigned long phys_address = 0;page_directory = (unsigned long *)(kernel_mem_pool->get_frame() * PAGE_SIZE);unsigned long * page_table = (unsigned long *)(kernel_mem_pool->get_frame() * PAGE_SIZE);for(unsigned int i = 0; i<ENTRIES_PER_PAGE;i++){page_table[i] = phys_adress | 3;phys_adress += PAGE_SIZE;}page_directory[0] = (unsigned long) page_table | 3;for(unsigned int i = 1;i < ENTRIES_PER_PAGE;i++){page_directory[i] = 0 | 2;}void PageTable::enable_paging(){write_cr3 ((unsigned long ) (current_page_table_>page_directory));write_cr0(read_cr0() | 0x80000000);}void PageTable::handle_fault(REGS * _r){unsigned int page_fault_addr = read_cr2();unsigned long* page_table;Console::putui(page_fault_addr);Console::puts("\n");unsigned int page_dir_entry = page_fault_addr >> 22;unsigned int page_tab_entry = (page_fault_addr & (0x03FF << 12)) >> 12;unsigned long page_table_addr = current_page_table->page_directory[page_dir_entry];if((page_fault_addr & 0x01) == 0){unsigned long new_page_table_addr = kernel_mem_pool ->get_frame() *PAGE_SIZE;page_table =(unsigned long*)(ew_page_table_addr);current_page_table->page_directory[page_dir_entry] = ( unsigned long)new_page_table_addr | 3;for( unsigned int i = 0;i< ENTRIES_PAR_PAGE; i++){page_table[i] = 0x00;}}else {page_table =(unsigned long*)(page_table_addr &0xfffff000);}unsigned long free_frame_no = process_mem_pool ->get_frame();page_table[page_tab_entry] = (free_frame_no *PAGE_SIZE) | 7;}8）编写Makefile文件执行makefile文件，即make –f makefile.linux 3.3调试分析修改bochsrc.bxrc文件，增加display_library:sdl属性去掉所有用户的可执行属性增加copykernel.sh文件的可执行属性建立/mnt/floppy目录修改引导程序copykernel.sh文件，添加强制卸载属性。