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Let's assume a cluster w/ 4 cores and one DSU. The core have L1/L2 private data cache. There is a L3 cache in DSU, shared by cores in the cluster. Here are the questions:
#1. For a read access marked as inner shareable, if the inner snoops inside DSU missed, will DSU issue snoops to the external fabric (say CMN) or just ReadNoSnoop to external memory directly?
#2. For a read access marked as outer shareable, will DSU snoop inside the inner domain firstly then go to outer domain by snooping fabric if no luck in inner snooping？
Many thanks.
For (2), the outer share ability domain is a super-set of the inner-domain. So while exact implementations might vary, the design would need to somehow know if the needed location was in any of the inner-domain PE's caches.