Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo

From: Paul E. McKenney
Date: Wed Mar 06 2019 - 12:26:13 EST


On Wed, Mar 06, 2019 at 05:58:31PM +0100, Peter Zijlstra wrote:
> On Thu, Mar 07, 2019 at 12:46:05AM +0900, Akira Yokosawa wrote:
> > So, I'm looking at the macro RELOC_HIDE() defined in include/linux/compiler-gcc.h.
>
> > Am I the only one who was not aware of this gcc-specific macro?
>
> It's one I regularly see, but had forgotten about in this context.
>
> However; you can also fix things by adding asm volatile ("":::"memory");
> in places.
>
> But that's not really the point; I would really rather have a cmdline
> knob to fix things. That way we can compile the kernel with and without
> and look for differences. -fno-unicorns or something :-)
>
> While I understand some compiler people revel in UB and love to make
> unicorns happen, I think in this case the produces result is utterly
> insane.

Because I couldn't resist...

https://raphlinus.github.io/assets/Anything_is_Possible_scaled.jpg

Thanx, Paul