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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E8251C433F5 for ; Sat, 28 May 2022 20:36:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YAxYsuzznkaI8La6AT0eUi9WNuCyaVfFzXuke/tG13s=; b=NpEIGkETT5vZbl z13wyd038mPOsUqiNviXKP7APYrR9ymZuLm+WLy80iQpmrpRg4TDQlB7pYqgKkEDHkt8daLZ8CO71 oyA3YmpnhPMICq783Duf9bT5JXX1GJlbwnc74fAOs7PwGSLTBzMq/flpUJdKDgySLvxNjRUCVC823 yvIBOulqkXPJJYA/8iSLn9fIbi4uJhsHxV3dRpgTxqP1aMQ6UnipUdfgdlUbkFVjXgdLyfEni+Idq gDcgRl4Kvg2dEF2DjyhJeU09lpDtO5me63ibQZqn/rTBMRHq12XBAhq5ncN2syLr2eOtx9tiEKM1n Rj4vmMV7OouMf0bkgqnQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nv39I-002iBi-3E; Sat, 28 May 2022 20:35:00 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nv39E-002i5K-GL for linux-arm-kernel@lists.infradead.org; Sat, 28 May 2022 20:34:58 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding: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=sVwMCmxLWsbsfDuisFxMS45pxNxsdph6vk/Q4MCnxVs=; b=svLxRgQOL9LJ6eX13vc1DeR5AC 7C0eYQF9MVCNok8ATdfWn8yWwjY9ZDAWnPd3UhJLNgQG/kcMhy4N7hynylYbmgz+cMNuuSEBYozlV Gusv3XEcuLGJHOQvlAKD0cJ87v8vDUBCneaD1tmgDaFuA7lXYtbeyD9eRNgEOdL4Z2xiN0tJW+YRf QW3HUhR3meFNqGRY9fbbGwgvkkVutHvzAn0D7uFK1ss3hdwf/9xvSsJEOqeny70pbjREu3VbjWxN2 mVS8zjMtfnnKll17XAbcdpAo6crx/N8mMno0Mc6ShDm3dM/TaDVEr/pLYkUjQRG3kDx4jMwgXyfS3 +K+q/2Kg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:60864) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nv36j-0001eB-5u; Sat, 28 May 2022 21:32:22 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1nv36Z-0008Aq-Ix; Sat, 28 May 2022 21:32:11 +0100 Date: Sat, 28 May 2022 21:32:11 +0100 From: "Russell King (Oracle)" To: Linus Torvalds Cc: Sudip Mukherjee , Arnd Bergmann , Viresh Kumar , Shiraz Hashim , Jani Nikula , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , dri-devel , Linux Kernel Mailing List , Linux ARM , SoC Team Subject: Re: mainline build failure due to f1e4c916f97f ("drm/edid: add EDID block count and size helpers") Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220528_133456_584146_5FCB52F0 X-CRM114-Status: GOOD ( 12.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Sat, May 28, 2022 at 11:08:48AM -0700, Linus Torvalds wrote: > This smells like a compiler bug triggered by "there's a 16-bit member > field in that gtf2 structure, and despite it being packed and aligned > to 1, we somehow still align the size to 2". It's an age old thing, it's no compiler bug, and it's completely compliant with the C standards. Implementations are permitted by the C standard to pad structures and unions how they see fit - and some do if it makes sense for performance. The mistake is that people forget this detail, and they expect structs and unions to be laid out a certain way - because it doesn't matter to the same extent on x86. However, as older ARM CPUs could not do unaligned loads, ensuring that things were naturally aligned made complete sense, even if it meant that people who assume the world is x86 got tripped up - the only way around that would be to make every load very expensive. It's not "align to size of 2" in OABI, it tends to be align to a multiple of 4, because the underlying architecture is 32-bit. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel