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#2
Valenciax2020-06-26 05:54
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程序代码： .set noreorder
.globl _start
.globl start
_start:
start:
.globl stack
stack = start - 0x4000
mtc0 zero, COP_0_STATUS_REG
mtc0 zero, COP_0_CAUSE_REG
li t0, SR_BOOT_EXC_VEC
mtc0 t0, COP_0_STATUS_REG
la sp, stack
bal uncached /* Switch to uncached address space */
nop
uncached:
or ra, UNCACHED_MEMORY_ADDR
j ra
nop
.globl _start
.globl start
_start:
start:
.globl stack
stack = start - 0x4000
mtc0 zero, COP_0_STATUS_REG
mtc0 zero, COP_0_CAUSE_REG
li t0, SR_BOOT_EXC_VEC
mtc0 t0, COP_0_STATUS_REG
la sp, stack
bal uncached /* Switch to uncached address space */
nop
uncached:
or ra, UNCACHED_MEMORY_ADDR
j ra
nop
引导代码bal为什么能够跳转到uncached执行（地址怎么计算的）？目的是什么？