Re: [PATCH 8/9] RISC-V: User-facing API

[Christoph Hellwig]

On Thu, Jul 06, 2017 at 09:55:03AM +0100, Will Deacon wrote:
> Agreed on the indirection; it feels like this is something that should be in
> the vDSO, which could use the cmpxchg instruction if it's available, or
> otherwise just uses plain loads and stores.

Even that seems like a lot of indirection for something that is in
the critical fast path for synchronization.  I really can't understand
how a new ISA / ABI could even come up with an idea as stupid as making
essential synchronization primitives optional.