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Is microSCU required for multi-cores to maintain coherency?

R5, for example, has microSCU (snoop control unit) as an option. Is this necessary for, say, a dual-core to maintain coherency between the two or for the two to maintain coherency with external processors?

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tjones95134 over 1 year ago +1 suggested

The answer to my question is 'yes'. I discovered when configuring the R5 that the config sanity checking checks if SCU is present and flags and error if: o Only 1 processor o No D-Cache present This...
Martin Weidmann over 1 year ago in reply to tjones95134 +1 verified

Note, the ACP (and micro-SCU) are there to give coherency with external accelerators, not to maintain coherency between the Cortex-R5 cores. From the TRM: A twin-CPU Cortex-R5 group is not an MP-cluster...

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0 tjones95134 over 1 year ago in reply to Martin Weidmann

Martin,

You are correct for stand-alone Cortex-R5 - which doesn't have a MICRO_SCU option. I neglected to mention that I was working on Cortex-R5 SOC-400 PIL, which does have it.

Thanks for your clarification.

~Tom
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0 tjones95134 over 1 year ago in reply to Martin Weidmann

Martin,

You are correct for stand-alone Cortex-R5 - which doesn't have a MICRO_SCU option. I neglected to mention that I was working on Cortex-R5 SOC-400 PIL, which does have it.

Thanks for your clarification.

~Tom
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