linux arm h/w 页表是什么？

linuxfellow

Arm pte table前2K是linux 页表, 高2k是h/w页表， 这两个页表究竟是啥？ 如何理解？
/*
* Allocate one PTE table.
*
* +--------------+ 0
* | Linux pt 0 |
* +--------------+
* | Linux pt 1 |
* +--------------+ 2048
* | h/w pt 0 |
* +--------------+
* | h/w pt 1 |
* +--------------+
*/
From d30e45eeabefadc6039d7f876a59e5f5f6cb11c6 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Tue, 16 Nov 2010 00:16:01 +0000
Subject: [PATCH] ARM: pgtable: switch order of Linux vs hardware page tables
This switches the ordering of the Linux vs hardware page tables in
each page, thereby eliminating some of the arithmetic in the page
table walks. As we now place the Linux page table at the beginning
of the page, we can deal with the offset in the pgt by simply masking
it away, along with the other control bits.
This also makes the arithmetic all be positive, rather than a mixture.

塑料袋

ARM的每个PTE都有两份的

因为ARM的pte信息不足，缺少access及dirty位，所以搞了个假的，在真正设置pte时，会根据假的推算真的。

linuxfellow

回复 2# 塑料袋
不知哪里有这样的信息：如何从假的推算真的？

   

塑料袋

C文件的注释里就有

真假相差2048字节，换算的过程大概在entry.S里，一个好像叫set_pte_ext的函数里。