1.5.5. disable MMU

	/*
	 * disable MMU stuff and caches
	 */
	mrc	p15, 0, r0, c1, c0, 01

1

此处，对应的值为：

rd为r0=0

CRn为C1

CRm为C0

opcode_2为0

即，此行代码是将r0的值，即0，写入到CP15的寄存器1中。

寄存器1的相关的定义为：

http://www.heyrick.co.uk/assembler/coprocmnd.html

StrongARM SA110

  • Register 1 - Control (read/write)

    All values set to 0 at power-up.

    • Bit 0 - On-chip MMU turned off (0) or on (1)
    • Bit 1 - Address alignment fault disabled (0) or enabled (1)
    • Bit 2 - Data cache turned off (0) or on (1)
    • Bit 3 - Write buffer turned off (0) or on (1)
    • Bit 7 - Little-endian operation if 0, big-endian if 1
    • Bit 8 - System bit - controls the MMU permission system
    • Bit 9 - ROM bit - controls the MMU permission system
    • Bit 12 - Instruction cache turned off (0) or on (1)”

所以，对应内容就是，向bit[CRm]中写入opcode_2，即向bit[0]写入0，对应的作用为“On-chip MMU turned off”，即关闭MMU。

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1.5.4. cpu_init_crit 起始页 1.5.6. clear bits