Method openPageMechanism

lab7/src/4/src/kernel/memory.cpp:109–144

}

void MemoryManager::openPageMechanism()
{
    // 页目录表指针
    int *directory = (int *)PAGE_DIRECTORY;
    //线性地址0~4MB对应的页表
    int *page = (int *)(PAGE_DIRECTORY + PAGE_SIZE);

    // 初始化页目录表
    memset(directory, 0, PAGE_SIZE);
    // 初始化线性地址0~4MB对应的页表
    memset(page, 0, PAGE_SIZE);

    int address = 0;
    // 将线性地址0~1MB恒等映射到物理地址0~1MB
    for (int i = 0; i < 256; ++i)
    {
        // U/S = 1, R/W = 1, P = 1
        page[i] = address | 0x7;
        address += PAGE_SIZE;
    }

    // 初始化页目录项

    // 0~1MB
    directory[0] = ((int)page) | 0x07;
    // 3GB的内核空间
    directory[768] = directory[0];
    // 最后一个页目录项指向页目录表
    directory[1023] = ((int)directory) | 0x7;

    // 初始化cr3，cr0，开启分页机制
    asm_init_page_reg(directory);

    printf("open page mechanism\n");
    
}