99 lines
3.3 KiB
Markdown
99 lines
3.3 KiB
Markdown
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<!--
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* Copyright : (C) 2022 Phytium Information Technology, Inc.
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* All Rights Reserved.
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*
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* This program is OPEN SOURCE software: you can redistribute it and/or modify it
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* under the terms of the Phytium Public License as published by the Phytium Technology Co.,Ltd,
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* either version 1.0 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the Phytium Public License for more details.
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*
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*
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* FilePath: mmu.md
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* Date: 2022-02-22 16:26:16
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* LastEditTime: 2022-02-22 16:26:16
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* Description: This file is for
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*
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* Modify History:
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* Ver Who Date Changes
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* ----- ------ -------- --------------------------------------
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-->
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# MMU
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## 1. 概述
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- 虚拟内存系统（VMSA）提供了一套内存管理单元（MMU）， 它控制着地址转换、访问权限和内存属性的确定和检查。
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- 地址转换过程将CPU使用的虚拟地址(VAs)映射到物理内存系统的物理地址(PAs)上。
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- 在本SDK中 aarch32 state 采用 section 格式的转换表
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- 在本SDK中 aarch64 state 采用 4KB 粒度 格式的转换表
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## 2. 功能
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- MMU功能支持用户根据需要修改MMU表的默认内存属性。
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## 3. 配置方法
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## 4. 应用示例
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"baremetal/example/system/amp/libmetal_test"
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"baremetal/example/system/amp/openamp"
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## 5. API参考
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### 5.1 用户定义
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/* 访问权限 */
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```
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#define MT_P_NA_U_NA /* higher Exception level access=NA, user=NA */
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#define MT_P_RW_U_NA /* higher Exception level access=RW, user=NA */
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#define MT_P_RW_U_RO /* higher Exception level access=RW, user=RO */
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#define MT_P_RW_U_RW /* higher Exception level access=RW, user=RW */
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#define MT_P_RO_U_NA /* higher Exception level access=RO, user=NA */
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#define MT_P_RO_U_RO /* higher Exception level access=RO, user=RO */
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```
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/* 内存属性参数 */
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```
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#define MT_DEVICE_NGNRNE /* Device-nGnRnE , Outer Shareable */
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#define MT_DEVICE_NGNRE /* Device-nGnRE , Outer Shareable */
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#define MT_NORMAL_WT /* Outer and Inner Write-Through, Read-Allocate No Write-Allocate , Outer Shareable */
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#define MT_NORMAL_WB_WCN /* Outer and Inner Write-Back, Read-Allocate No Write-Allocate , Outer Shareable */
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#define MT_NORMAL_NC /* Outer and Inner Non-cacheable , Outer Shareable , Outer Shareable */
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#define MT_NORMAL /* Outer and Inner Write-Back, Read-Allocate Write-Allocate , Outer Shareable , Outer Shareable */
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```
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### 5.2 用户API接口
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- 此函数用于配置转换表中地址对应条目的内存属性与访问权限
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```c
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void FSetTlbAttributes(uintptr addr, fsize_t size, u32 attrib);
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```
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Note:
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aarch32 state 采用 section 页表，由此addr 建议采用1MB 地址对齐，size 建议为MB的整数倍。
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aarch64 state 采用 4KB 粒度 页表，由此addr 建议采用4KB 地址对齐，size 建议为4KB的整数倍。
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Input:
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- addr ， 需要为内存区域设置属性与权限的起始地址
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- size ， 内存区域的范围
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- attrib，指定内存区域的属性 ,内存属性的取值由 访问权限 与 内存属性参数 组成，具体类型参考 ### 5.1 用户定义
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Return:
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- void
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