[yvdriess]

Nope. First, it's not L3 cache and secondly comparing 3D-stacked in-package memory (MCDRAM, HBM, HBM2) with your examples is misleading. https://en.wikipedia.org/wiki/High_Bandwidth_Memory

[fulafel]

You can configure the near memory to be used as cache or directly addressed memory as desired. Users of existing codes will configure it as cache.

[yvdriess]

Direct addressing is the preferred configuration. Only if your existing code's working set does not fit in MCDRAM does the cache configuration make sense.

It might sound pedantic on my part, but 'it can act as cache' is very different in practice from 'It is a cache'.