Re: [PATCH v3 1/2] RISC-V: Define sys_riscv_flush_icache when SMP=n

From: Christoph Hellwig
Date: Tue Aug 14 2018 - 09:35:56 EST

On Fri, Aug 10, 2018 at 11:27:37AM -0700, Palmer Dabbelt wrote:
> I'm not sure. We can implement the syscall fine in !SMP, it's just that the
> vDSO is expected to always eat these calls because in non-SMP mode you can
> do a global fence.i by just doing a local fence.i (there's only one hart).
> The original rationale behind not having the syscall in non-SMP mode was to
> limit the user ABI, but on looking again that seems like it's just a bit of
> extra complexity that doesn't help anything. It's already been demonstrated
> that nothing is checking the error because it's been silently slipping past
> userspace for six months, so the extra complexity seems like it'll just
> cause someone else to have to chase the bug in the future.
> But I'm really OK either way. Is there a precedent for what to do here?

I don't know of any.