Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754421AbbKWUiv (ORCPT ); Mon, 23 Nov 2015 15:38:51 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:58226 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735AbbKWUit (ORCPT ); Mon, 23 Nov 2015 15:38:49 -0500 Date: Mon, 23 Nov 2015 12:38:47 -0800 From: Stephen Boyd To: Arnd Bergmann Cc: Christopher Covington , Nicolas Pitre , Russell King - ARM Linux , Peter Maydell , =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= , "linux-arm-msm@vger.kernel.org" , lkml - Kernel Mailing List , Steven Rostedt , arm-mail-list Subject: Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions Message-ID: <20151123203847.GB19156@codeaurora.org> References: <1448068997-26631-1-git-send-email-sboyd@codeaurora.org> <8472808.1HUuK2O5nn@wuerfel> <56531F4F.9010100@codeaurora.org> <105706554.vF12QZslMx@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <105706554.vF12QZslMx@wuerfel> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4168 Lines: 121 On 11/23, Arnd Bergmann wrote: > On Monday 23 November 2015 09:14:39 Christopher Covington wrote: > > On 11/23/2015 03:15 AM, Arnd Bergmann wrote: > > > On Sunday 22 November 2015 21:36:45 Nicolas Pitre wrote: > > >> On Sun, 22 Nov 2015, Arnd Bergmann wrote: > > > > > > Ok, thanks a lot! So the reporting in /proc/cpuinfo clearly matches > > > the actual features, and we can just treat this as no LPAE / no IDIV > > > for kernel compilation, as nobody ever seems to use THUMB2_KERNEL > > > in practice. > > > > > > PJ4-MP is like Cortex-A15/A7/A12/A17 and supports both IDIV and LPAE, > > > which leaves the question whether Scorpion or Krait do the same as > > > well, or whether they are outliers and need a special configuration. > > > > LPAE is only supported in the Krait 450. > > > > http://www.anandtech.com/show/7537/qualcomms-snapdragon-805-25ghz-128bit-memory-interface-d3d11class-graphics-more > > > > I'm pretty sure idiv support came earlier, but I don't have the > > specifics on hand. > > I have seen that article, but didn't trust it as a canonical > source of information here. > > If you can confirm that it's right, that would mean that we > don't support LPAE on mach-qcom, as the only SoC with Krait 450 > seems to be APQ8084, and mainline Linux doesn't run on that. arch/arm/boot/dts/qcom-apq8084.dtsi exists in the mainline kernel. We support more than what's in the Kconfig language under mach-qcom. And yes LPAE is supported by apq8084 (as is IDIV). Here's the /proc/cpuinfo on that device. # cat /proc/cpuinfo processor : 0 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 38.40 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x3 CPU part : 0x06f CPU revision : 1 processor : 1 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 38.40 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x3 CPU part : 0x06f CPU revision : 1 processor : 2 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 38.40 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x3 CPU part : 0x06f CPU revision : 1 processor : 3 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 38.40 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x3 CPU part : 0x06f CPU revision : 1 Hardware : Qualcomm (Flattened Device Tree) Revision : 0000 Serial : 0000000000000000 > > The ones we do support are MSM8x60 (Scorpion), MSM8960 > (Krait-without-number),and MSM7874 (Krait 400). Do those all > support IDIV but not LPAE? > Krait supports IDIV for all versions. Scorpion doesn't support IDIV or lpae. Here's the output of /proc/cpuinfo on that device. # cat /proc/cpuinfo processor : 0 model name : ARMv7 Processor rev 2 (v7l) BogoMIPS : 13.50 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32 CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x0 CPU part : 0x02d CPU revision : 2 processor : 1 model name : ARMv7 Processor rev 2 (v7l) BogoMIPS : 13.50 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32 CPU implementer : 0x51 CPU architecture: 7 CPU variant : 0x0 CPU part : 0x02d CPU revision : 2 Hardware : Qualcomm (Flattened Device Tree) Revision : 0000 Serial : 0000000000000000 -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- 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/