This has undesired effects on some GIC registers, for eg GICC_IAR register can only read once to acknowledge the interrupt.
这不希望一些GIC寄存器效果，如GICC_IAR寄存器只能读一次承认中断。
Class Code the Class Code register is read-only and is used to identify the generic function of the device and, in some cases, a specific register-level programming interface.
本寄存器是只读的，被用来标识该设备类属的功能，而且在有些情况下，是一个寄存器级的编程接口。
只读地址寄存器 ROAR?。
只读地址寄存器 ROAR?。
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