This isn't just a RISC-V thing. There is significant bureaucracy in Linux to push back on vendors doing even dumber stuff with hardware in the future; that was

This isn't just a RISC-V thing. There is significant bureaucracy in Linux to push back on vendors doing even dumber stuff with hardware in the future; that was a lot of the discussion around my patches to support the M1. We have to support the hardware, but do so in a way that does not encourage vendors to push things further (we know Apple doesn't care about any of this, but e.g. nobody wants Qualcomm or Broadcom, who do build platforms that intend to run Linux as a first-class citizen, to get any silly ideas). But this is all stuff you work out by looking at the finer points of the implementation and doing it in a way that does not encourage further divergence; certainly throwing stuff in staging isn't how you do it. Ultimately, Linux's goal is to support the hardware; that support may be done in such a way to discourage future "bad" hardware, but it still has to be there as proper support, if the features have merit. For example, we have a patch series in review right now to support KVM on the M1, because (surprise surprise) Apple did some nonstandard stuff there too. It's definitely not going in staging though :) On the other hand, it's less likely that mainline Linux will quickly gain support for, say, things like Apple's proprietary security features (their pointer auth extensions, paging protection stuff, etc) unless there are similar mechanisms implemented in other vendors' CPUs, because those things provide only marginal benefit for end users of specific systems, and Linux has bigger security fish to fry first.