Uboot源码：

/*
 * Setup vector:
 * (OMAP4 spl TEXT_BASE is not 32 byte aligned.
 * Continue to use ROM code vector only in OMAP4 spl)
 */
#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
	/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
	mrc	p15, 0, r0, c1, c0, 0	@ Read CP15 SCTLR Register
	bic	r0, #CR_V		@ V = 0
	mcr	p15, 0, r0, c1, c0, 0	@ Write CP15 SCTLR Register

	/* Set vector address in CP15 VBAR register */
	ldr	r0, =_start
	mcr	p15, 0, r0, c12, c0, 0	@Set VBAR
#endif

1.设置中断向量表基地址选择位V

为 0 的话中断向量表基地址为 0X00000000，软件可以使用 VBAR 来重映射此基地址.

/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
mrc	p15, 0, r0, c1, c0, 0	@ Read CP15 SCTLR Register
bic	r0, #CR_V		@ V = 0
mcr	p15, 0, r0, c1, c0, 0	@ Write CP15 SCTLR Register

2.中断向量表重定位。

/* Set vector address in CP15 VBAR register */
ldr	r0, =_start
mcr	p15, 0, r0, c12, c0, 0	@Set VBAR