Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759757AbbKUWLq (ORCPT ); Sat, 21 Nov 2015 17:11:46 -0500 Received: from unicorn.mansr.com ([81.2.72.234]:58330 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750891AbbKUWLp convert rfc822-to-8bit (ORCPT ); Sat, 21 Nov 2015 17:11:45 -0500 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Arnd Bergmann Cc: linux-arm-kernel@lists.infradead.org, Stephen Boyd , linux-arm-msm@vger.kernel.org, Steven Rostedt , linux-kernel@vger.kernel.org, Nicolas Pitre Subject: Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions References: <1448068997-26631-1-git-send-email-sboyd@codeaurora.org> <7199523.6J0A1gxY4q@wuerfel> <5239BA2A-BCD9-4A8C-BC34-F48603137E08@mansr.com> <6160413.CulAvzVaQj@wuerfel> Date: Sat, 21 Nov 2015 22:11:36 +0000 In-Reply-To: <6160413.CulAvzVaQj@wuerfel> (Arnd Bergmann's message of "Sat, 21 Nov 2015 22:00:16 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2128 Lines: 47 Arnd Bergmann writes: > On Saturday 21 November 2015 20:45:38 M?ns Rullg?rd wrote: >> On 21 November 2015 20:39:58 GMT+00:00, Arnd Bergmann wrote: >> >On Friday 20 November 2015 17:23:14 Stephen Boyd wrote: >> >> This is a respin of a patch series from about a year ago[1]. I >> >realized >> >> that we already had most of the code in recordmcount to figure out >> >> where we make calls to particular functions, so recording where >> >> we make calls to the integer division functions should be easy enough >> >> to add support for in the same codepaths. Looking back on the thread >> >> it seems like Mans was thinking along the same lines, although it >> >wasn't >> >> obvious to me back then or even over the last few days when I wrote >> >this. >> > >> >Shouldn't we start by allowing to build the kernel for -march=armv7ve >> >on platforms that allow it? That would seem like a simpler change >> >and likely generate better code for most people, except when you >> >actually >> >care about running the same binary kernel on older platforms. >> > >> >I tried to get a complete list of CPU cores with idiv, lpae and >> >virtualization support at some point, but I don't remember the >> >details for all Qualcomm and Marvell cores any more, to create the >> >complete configuration matrix. IIRC, all CPUs that support >> >virtualization also do lpae (they have to) and all CPUs that >> >do lpae also do idiv, but the opposite is not true. >> > >> >> The ARM ARM says anything with virt has idiv, lpae doesn't matter. > > Ok, and anything with virt also has lpae by definition. The question is > whether we care about using idiv on cores that do not have lpae, or that > have neither lpae nor virt. The question is, are there any such cores? GCC doesn't know of any, but then it's missing most non-ARM designs. -- M?ns Rullg?rd mans@mansr.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/