linux-kernel - RE: [RFC PATCH 0/8] Rework READ

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Message-ID: <c1c18e9a4f144c6a92a250a206dfef02@AcuMS.aculab.com>
Date:   Mon, 13 Jan 2020 11:20:50 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Will Deacon' <will@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: RE: [RFC PATCH 0/8] Rework READ_ONCE() to improve codegen

From: Will Deacon
> Sent: 10 January 2020 16:56
...
> The rough summary of the series is:
> 
>   * Drop the GCC 4.8 workarounds, so that READ_ONCE() is a
>     straightforward dereference of a cast-to-volatile pointer.

What is the effect of using the changed code on older compilers (esp. x86-64)?
Requiring gcc > 4.8 is a significant bump.

	David

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