kinit();// physical page allocator: init kmem lock, and free pa from end to PHYSTOP(set to 0).kvminit();// alloc and create kernel page table: and map virtural address in kernel pagetable to address in pysical memory.kvminithart();// turn on paging: set satp to kernel pagetable...
3 uncached (已分配)未缓存的:没有缓存在物理存储器中的已分配页。 页表page table 存放在物理存储器一个数据结构,叫做页表(page table)。页表将虚拟页映射到物理页。页表就是一个PTE(page table entry,页表条目)的数组。虚拟地址空间中的每个页在页表中的一个固定偏移量处都有一个PTE。 PTE0 为null,无效、...
页目录指针表(Page Directory Pointer Table,PDP) 现在使用PDP表的物理地址并将低12位(867)清零,这12个位会在页表(Page Table Entries table)中被引用。 0x1ff48000+虚拟地址的38-30位乘上8作为偏移,以找到页目录表(Page Directory Table)的物理地址,结果是0x19d90867。 页目录表(Page Directory Table) 清零11...
Virtual memory(虚拟内存),顾名思义,是针对physical memory(物理内存)来的。 远古时期的计算机(五十年前的大型机或者三十年前的个人电脑)是不用虚拟内存的,那时候要想跑一个程序,必须先把整个程序加载到物理内存里才能执行。可是内存又小又贵,而人们不仅想跑大程序,还想同时跑好几个,有限的物理内存吃不消了可怎...
If the process needs additional memory at runtime, and if that memory is at a (virtual) address not within the 4 MB range managed by its page table, then a second page table needs to be provided, increasing the memory used to store the mappings by another 4 KB. Using this two level...
我们应该知道物理内存(Physical Memory)指的是硬件上的内存,即 RAM。它通常指的是插在主板上的内存条,给进程提供临时数据存储的设备。因为 CPU 可以直接从物理内存中读取数据和指令,所以物理内存又叫做主存。 虚拟内存(virtual memory,VM)又叫做虚拟存储(virtual storage),是一种内存管理技术。它是操作系统提供的一种...
Since consecutive pages of the page table in virtual memory reside in consecutive page frames in physical memory, a virtual address in the page tables can be translated to a physical address by adding the page frame number from the prototype page table entry to the virtual page number in the...
The basic mechanism for reading a word from memory involves the translation of a virtual, or logical, address, consisting of page number and offset, into a physical address, consisting of frame number and offset, using a page table. Because the page table is of variable length, depending on...
Virtual memory(虚拟内存) 现代处理器使用的是虚拟寻址的方式,CPU 通过访问虚拟地址(Virtual Address),经过翻译获得物理地址,才能访问内存。这个翻译过程由 CPU 中的内存管理单元(Memory Management Unit,缩写为 MMU)完成。 image.png 如上图所示:首先会在 TLB(Translation Lookaside Buffer)中进行查询,它表位于 CPU ...
0 How to use a page table to convert virtual address to physical address 14 Determining page numbers and offsets for given addresses 2 Converting virtual address to page table entry 0 Mapping between virtual and physical address in memory paging 1 How is the virtual address of t...