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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rUN87HHcT0D+VYtpGAgTAdZG4A7i97yXdShp42YthWM=; b=Z/gGPEVBs4iaELnb0B/9It+TQ/oRyJhDvQbsWnyWvaM7QOv4+Gj2+A9kbsa7MaOSsn WbGz37iF0gc5+MbSQQdLUCnVsU6MWgjGeDdD5JYbyO8ovEEvBVo9JPjLofy9s755tMsK bbBPPlcyb34ZyATCUOblTxzhH8eGOMawxLws1i1XkPTyYV0dXNSb6X1mWj9MO1YoaK83 kAD+aiZrLrpK5G66ZEyd37l7m0Wg5X7J3FJZOv1drn4o2IB9oJFG2I9OxjdG19L0SFNR /SM0wtuu1DxvT8tvqtL/jJuiJgrDdoCPdVSobUCFJHu0CFkVFrrOOISLLe11J4qMzcH/ t+fw== X-Gm-Message-State: AOAM530/H6qWE5cokIiMLvE0iVswcKtvLJNDRUypmKWDALzHvWStBz2j Hv+6acQ/frx/nkG0Wi8onR3PRyCCqvuxbLSoxh663A== X-Google-Smtp-Source: ABdhPJyMCCNt8i1Et0DyOsaJ8wbMi3m1E8cveJ16TjMymVl4lnUJDpBklfG7oZetuBRbt8rGyAQ/aXNQNKJmxsfRdtU= X-Received: by 2002:a9d:2788:: with SMTP id c8mr32372097otb.251.1594192556026; Wed, 08 Jul 2020 00:15:56 -0700 (PDT) MIME-Version: 1.0 References: <20200630173734.14057-1-will@kernel.org> <20200630173734.14057-19-will@kernel.org> <20200701170722.4rte5ssnmrn2uqzg@bakewell.cambridge.arm.com> <20200702072301.GA15963@willie-the-truck> <20200706160023.GB10992@arm.com> <20200706163455.GV9247@paulmck-ThinkPad-P72> <20200706170556.GE10992@arm.com> <20200706173628.GZ9247@paulmck-ThinkPad-P72> <20200707102915.GI10992@arm.com> <20200707225122.GJ9247@paulmck-ThinkPad-P72> In-Reply-To: From: Marco Elver Date: Wed, 8 Jul 2020 09:15:44 +0200 Message-ID: Subject: Re: [PATCH 18/18] arm64: lto: Strengthen READ_ONCE() to acquire when CLANG_LTO=y To: Nick Desaulniers X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200708_031600_197077_3AAEB80D X-CRM114-Status: GOOD ( 16.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , "Michael S. Tsirkin" , Peter Zijlstra , Catalin Marinas , Jason Wang , virtualization@lists.linux-foundation.org, Will Deacon , Arnd Bergmann , Alan Stern , Sami Tolvanen , Matt Turner , kernel-team , Dave Martin , Kees Cook , "Paul E. McKenney" , Boqun Feng , Josh Triplett , Steven Rostedt , Ivan Kokshaysky , Linux ARM , Richard Henderson , LKML , linux-alpha@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 8 Jul 2020 at 01:01, Nick Desaulniers wrote: > > I'm trying to put together a Micro Conference for Linux Plumbers > conference focused on "make LLVM slightly less shitty." Do you all > plan on attending the conference? Would it be worthwhile to hold a > session focused on discussing this (LTO and memory models) be > worthwhile? I would welcome sessions on LLVM, and would try to attend. Apart from general improvements to the LLVM ecosystem, we should also emphasize the benefits LLVM provides and how we can enable them (one reason we want LTO is to get CFI). Regarding LTO and memory models, I'm not sure. Given the current state of things, such a discussion needs to be carefully framed to not go in circles, because we're trying to figure out things at the intersection of architecture, what the compiler does, the C standard, and the kernel wants. And because some of these boxes are difficult to change (standard, arch, compiler) or difficult to precisely define behaviour (compiler), we might end up going in circles. From what I see there are efforts to fix the situation at the root (standard), and we might have means to get the compiler to tell us what it's doing. But these happen extremely slowly. So, if we do this, we need to be careful to not end up re-discussing what we discussed here, but rather try and make it a continuation that hopefully leads to some constructive output. Thanks, -- Marco _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel