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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 3E805C0044C for ; Wed, 7 Nov 2018 17:59:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D430E2081D for ; Wed, 7 Nov 2018 17:59:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="sNzkE7x6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D430E2081D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731456AbeKHDa1 (ORCPT ); Wed, 7 Nov 2018 22:30:27 -0500 Received: from twosheds.infradead.org ([90.155.92.209]:35630 "EHLO twosheds.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728166AbeKHDa1 (ORCPT ); Wed, 7 Nov 2018 22:30:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=twosheds.20170209; h=Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:To:From:Subject:Date:References:In-Reply-To: Message-ID:Sender:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=5c6nkgpCvsjPHI2lAEAZ29rfXiAahTvEwXyfklBliLc=; b=sNzkE7x6arDD2o3Yd/GvrAbdW xQCAJjfl74S2rKBenF9xWg3ORhC/wTLdd5iCAnaBcsx/0LYz6MSDr2F+YWdDWeXbeJdUdiriniBve vM9EY6hBldDZ+DA27N0pEX4AKyl/lIW05gnvCmFu/WTndMXD/4luVvJqrNf+jCRPhPcySW3lta8Bi 4yw5O0G2Uw+7f99ZWUfWRJpRmOMnRmUC7dzweKvp27lQO+QrwLRp1A6ekigVNPgZIk9C3DL8dLYj1 YWYVUoTSPioCQ87RVEA4xBsK6z1G+HvYi3bv+fIdv3CSIkKApZFvCpX/Xd5RrBTwmfgPagh52PBy6 kuoUFGQuA==; Received: from localhost ([127.0.0.1] helo=twosheds.infradead.org) by twosheds.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gKS6P-00AboG-A8; Wed, 07 Nov 2018 17:58:53 +0000 Received: from 213.205.242.122 (SquirrelMail authenticated user dwmw2) by twosheds.infradead.org with HTTP; Wed, 7 Nov 2018 17:58:53 -0000 Message-ID: In-Reply-To: <20181107173303.slnb3i2d6ufaonp7@zorba> References: <20181106214928.40020-1-nkela@cisco.com> <921b0f78cf67d7307a0555e1fd6f2c2976310adc.camel@infradead.org> <1e4c066d1896e2a0b8b146253d34d05cc4f9ab36.camel@infinera.com> <8b08e8b992093453bb2b9caff8cff08c.squirrel@twosheds.infradead.org> <20181107173303.slnb3i2d6ufaonp7@zorba> Date: Wed, 7 Nov 2018 17:58:53 -0000 Subject: Re: [PATCH] jffs2: implement mount option to configure endianness From: "David Woodhouse" To: "Daniel Walker" Cc: "David Woodhouse" , "Joakim Tjernlund" , "nkela@cisco.com" , "linux-kernel@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "xe-linux-external@cisco.com" User-Agent: SquirrelMail/1.4.22-21.fc27 MIME-Version: 1.0 Content-Type: text/plain;charset=utf-8 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-SRS-Rewrite: SMTP reverse-path rewritten from by twosheds.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Wed, Nov 07, 2018 at 04:12:14PM -0000, David Woodhouse wrote: >> >> > Yes, this may slow things down. I am not sure I agree with the impl. >> > either. >> > Could one not make cpu_to_je_X/jeX_to_cpu a function ptr which is set >> to >> > a func. with the correct endian? >> >> On x86 retpoline would make that quite slow. > > Is x86 the largest consumer of jffs2 ? Certainly not. I'm not sure which architectures do have Spectre V2 mitigations which make indirect branches expensive now... perhaps there is no intersection with the cases where we really care about JFFS2 being CPU-bound? -- dwmw2