tiny6410的MMU的配置于使用

来源：互联网发布：动态分配二维数组编辑：程序博客网时间：2024/04/29 15:14

由手册《Arm1176jzfs》的第六节可知，tiny6410MMU的配置与使用需要分三步：

1、建立一级页表

/*
* 用于段描述符的一些宏定义
*/
#define MMU_FULL_ACCESS (3 << 10) /* 访问权限 */
#define MMU_DOMAIN (0 << 5) /* 属于哪个域 */
#define MMU_SPECIAL (1 << 4) /* 必须是1 */
#define MMU_CACHEABLE (1 << 3) /* cacheable */
#define MMU_BUFFERABLE (1 << 2) /* bufferable */
#define MMU_SECTION (2 << 0) /* 表示这是段描述符 */

#define SECDESC (MMU_SECTION | MMU_SPECIAL | MMU_DOMAIN | MMU_FULL_ACCESS)
#define MMU_SECDESC_WB (MMU_FULL_ACCESS | MMU_DOMAIN | MMU_SPECIAL | MMU_CACHEABLE | MMU_BUFFERABLE | MMU_SECTION)

void create_page_table(void)
{
unsigned long *ttb = (unsigned long *)0x50000000;
unsigned long vaddr, paddr;

vaddr = 0xA0000000;
paddr = 0x7f000000;
*(ttb + (vaddr >> 20)) = (paddr & 0xFFF00000) | MMU_SECDESC;
/*内存映射*/
vaddr = 0x50000000;
paddr = 0x50000000;
while (vaddr < 0x54000000)
{
*(ttb + (vaddr >> 20)) = (paddr & 0xFFF00000) | MMU_SECDESC_WB;
vaddr += 0x100000;
paddr += 0x100000;
}

}

2、写入TTB

/*设置TTB*/
"ldr r0, =0x50000000\n"
"mcr p15, 0, r0, c2, c0, 0\n"

3、使能MMU

void mmu_init()
{
__asm__(

/*设置TTB*/
"ldr r0, =0x50000000\n"
"mcr p15, 0, r0, c2, c0, 0\n"

/*不进行权限检查*/
"mvn r0, #0\n"
"mcr p15, 0, r0, c3, c0, 0\n"


/*使能MMU*/
"mrc p15, 0, r0, c1, c0, 0\n"
"orr r0, r0, #0x0001\n"
"mcr p15, 0, r0, c1, c0, 0\n"
:
:
);
}

然后在主函数中调用这两个函数就可以了。

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