From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F6B3C433ED for ; Fri, 14 May 2021 13:03:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D10A1613B5 for ; Fri, 14 May 2021 13:03:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233843AbhENNFA (ORCPT ); Fri, 14 May 2021 09:05:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:49480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231518AbhENNE6 (ORCPT ); Fri, 14 May 2021 09:04:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F07B461457; Fri, 14 May 2021 13:03:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620997427; bh=KjRucVq9b2NKDaj10nQp3ecBtpjWikZo5h6VILTp9TQ=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=ovF/DZ6vdNyVMSH9t0zjMiEagYR721FRrBVU2xZxXX/OUhYjI4DoeKwouVrElnjNo H2LSDPkvaHREyrn1HyHd22hBkz3doo6H4OkJrDEXpJxqK/vktxIuA+Y7acAYuukBaa 8O0eESoVXTaqfbi08ympBP0C9YMyag7kUEqEptmhtLOP4nWQVjNY971q4Zvmp63YMt FApG43bQoRmB4kFdndQzCDNsl0JV6NwuAMLOJTgNrK92jp4knsyOUt4/jlG789UKl4 nQaqjm0JUA5D0nUp8/StBDRTX5A//K7DIJJsrFgQEHzMgV0l+g4iKzmuREdaMda1QZ 5UKkdWqvLttRg== Received: by mail-wr1-f51.google.com with SMTP id n2so30044378wrm.0; Fri, 14 May 2021 06:03:46 -0700 (PDT) X-Gm-Message-State: AOAM530KCJZ25nhLNBkcuOGsrukBadGFOwRVs7o/kskMcnBcQNwdUi+J h0h3Qwac+7v5/Xe/g6Jn0wrMUz57wfFV2BMBHOI= X-Google-Smtp-Source: ABdhPJzlvCIkpR1F+kgydYHRKzdkFDddvZpYrU9rVtIDsh8sEqa4UTJsy0hLf91X5lxvVhxcxulzbSr4KB+n1tMKazY= X-Received: by 2002:a5d:6dc4:: with SMTP id d4mr60213997wrz.105.1620997425625; Fri, 14 May 2021 06:03:45 -0700 (PDT) MIME-Version: 1.0 References: <20210514100106.3404011-1-arnd@kernel.org> <20210514100106.3404011-6-arnd@kernel.org> <20210514114813.GJ10366@gate.crashing.org> In-Reply-To: <20210514114813.GJ10366@gate.crashing.org> From: Arnd Bergmann Date: Fri, 14 May 2021 15:02:43 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 05/13] powerpc: use linux/unaligned/le_struct.h on LE power7 To: Segher Boessenkool Cc: linux-arch , Vineet Gupta , linuxppc-dev , Linux Kernel Mailing List , Paul Mackerras , Linus Torvalds Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 14, 2021 at 1:48 PM Segher Boessenkool wrote: > On Fri, May 14, 2021 at 12:00:53PM +0200, Arnd Bergmann wrote: > > Little-endian POWER7 kernels disable > > CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS because that is not supported on > > the hardware, but the kernel still uses direct load/store for explicti > > get_unaligned()/put_unaligned(). > > > > I assume this is a mistake that leads to power7 having to trap and fix > > up all these unaligned accesses at a noticeable performance cost. > > > > The fix is completely trivial, just remove the file and use the > > generic version that gets it right. > > LE p7 isn't supported (it requires special firmware), and no one uses it > anymore, also not for development. It was used for powerpc64le-linux > development before p8 was widely available. Ok, thanks for the clarification. Should we just remove the Kconfig option for it then as further cleanup? Is there any other code such as alignment trap handling that could be removed if LE POWER7 gets dropped? Arnd