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Date: Tue, 9 Apr 2024 12:50:15 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>, rust-for-linux@vger.kernel.org,
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Subject: Re: [WIP 0/3] Memory model and atomic API in Rust
Message-ID: <20240409105015.GC21779@noisy.programming.kicks-ass.net>
References: <20240322233838.868874-1-boqun.feng@gmail.com>
 <ZgFVnar3nS4F8eIX@FVFF77S0Q05N>
 <ZgHly_fioG7X4wGE@boqun-archlinux>
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In-Reply-To: <ZgHly_fioG7X4wGE@boqun-archlinux>

On Mon, Mar 25, 2024 at 01:59:55PM -0700, Boqun Feng wrote:
> On Mon, Mar 25, 2024 at 10:44:45AM +0000, Mark Rutland wrote:
> [...]
> > > 
> > > * I choose to re-implement atomics in Rust `asm` because we are still
> > >   figuring out how we can make it easy and maintainable for Rust to call
> > >   a C function _inlinely_ (Gary makes some progress [2]). Otherwise,
> > >   atomic primitives would be function calls, and that can be performance
> > >   bottleneck in a few cases.
> > 
> > I don't think we want to maintain two copies of each architecture's atomics.
> > This gets painful very quickly (e.g. as arm64's atomics get patched between
> > LL/SC and LSE forms).
> > 
> 
> No argument here ;-)

Didn't we talk about bindgen being able to convert inline C functions
into equivalent inline Rust functions? ISTR that getting stuck on Rust
not having a useful inline asm.

But fixing all that in a hurry seems like the much saner path forward.