linux-kernel - Re: [RFC] LKMM: Add volatile

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Message-ID: <20210604155028.GF18427@gate.crashing.org>
Date:   Fri, 4 Jun 2021 10:50:28 -0500
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Will Deacon <will@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        paulmck@...nel.org, stern@...land.harvard.edu,
        parri.andrea@...il.com, boqun.feng@...il.com, npiggin@...il.com,
        dhowells@...hat.com, j.alglave@....ac.uk, luc.maranget@...ia.fr,
        akiyks@...il.com, linux-kernel@...r.kernel.org,
        linux-toolchains@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [RFC] LKMM: Add volatile_if()

On Fri, Jun 04, 2021 at 03:56:16PM +0200, Peter Zijlstra wrote:
> Urgh, I see. Compiler can't really help in that case either I'm afraid.
> They'll never want to modify loads that originate in an asm().

We never *can* change an asm template.  That is part of the fundamental
properties of inline asm.  We cannot even parse it!


Segher