compare with SiFive-E21

[zhouqinghua]

SiFive has released its lowpower RISC-V IP core(E21) whose application target is ultra-low power too.
compared with SiFive, what's the advantage of Hummingbird E200?
E21 is not opensource currently, I think most of its code is reused from "rocket chip".
SiFive's core ip cover from high end to low end: BOOM, U54, E51, E31, E21. it seems there are not so much opportunities left for other Startup Companies(work for RISC-V core).