Access problem of mtimercmp in a platform with multiple MTIMER devices


Tianyi Xia <tianshi.xty@...>
 

In the SiFive Core-Local Interruptor (CLINT) device , a core can access the mtimcmp register of all cores in the platform.

In the ACLINT spec, If a platform implements multiple MTIMER devices, such as multiple clusters, each cluster implements one MTIMER device, then a core may not be able to access the MTIMER devices of other clusters.

As I understand, it is not necessary for a core to access the mtimecmp of other cores. Is it possible to add a recommended software usage method to the ACLINT spec, for example, it is recommended that the software only use a core to access its own mtimcmp register, but not access mtimcmp of other cores. This can avoid the problem that the software uses a core to access the MTIMER devices of other clusters, but the hardware cannot support it.

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