From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753155AbaKFRGC (ORCPT ); Thu, 6 Nov 2014 12:06:02 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:54105 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751558AbaKFRF7 (ORCPT ); Thu, 6 Nov 2014 12:05:59 -0500 Date: Thu, 6 Nov 2014 17:05:48 +0000 From: Catalin Marinas To: Will Deacon Cc: Mark Rutland , "linux-arm-kernel@lists.infradead.org" , "ghackmann@google.com" , "ijc@hellion.org.uk" , Serban Constantinescu , "cross-distro@lists.linaro.org" , "linux-api@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH 0/1] arm64: Fix /proc/cpuinfo Message-ID: <20141106170548.GF19702@e104818-lin.cambridge.arm.com> References: <1414159000-27059-1-git-send-email-mark.rutland@arm.com> <20141106164311.GD19702@e104818-lin.cambridge.arm.com> <20141106165430.GH31605@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141106165430.GH31605@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 06, 2014 at 04:54:31PM +0000, Will Deacon wrote: > On Thu, Nov 06, 2014 at 04:43:12PM +0000, Catalin Marinas wrote: > > On Fri, Oct 24, 2014 at 02:56:39PM +0100, Mark Rutland wrote: > > > [d] Print different hwcaps dependent on the personality. > > > > > > This would allow for 32-bit and 64-bit applications to function > > > correctly, but for some 32-bit applications the personality would > > > need to be set explicitly by the user. > > > > Which makes this option actually in line with the uname -m behaviour. My > > vote goes for [d] with option [b] as a close alternative. > > > > > [1] arm, v3.17, Versatile Express A15x2 A7x3 coretile > > > Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm > > [...] > > > [2] arm64, v3.17, Juno platform > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 > > > > As an exercise, I'm trying to see what option [b] would look like when > > CONFIG_COMPAT is enabled: > > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae > > > > The duplicate strings would only be listed once (evtstrm, aes, pmull, > > sha1, sha2, crc32). New AArch64 features that we may expect to be > > optional on AArch32 could be prefixed with "a64". If they are missing > > entirely from AArch32, (like asimd), no need for the prefix. > > > > The advantage is that we don't need to check the personality but we have > > to assume that scripts would not search for substrings (sane people > > shouldn't do this anyway as the Features string can always be extended). > > And a big disadvantage is that I can imagine AArch64 applications checking > for "neon" instead of "asimd", which will break if they're run under kernels > without COMPAT support enabled. That's because they do stupid things and I they probably deserve to break ;). But I agree, there is a risk. > So I'm inclined to stick with Mark's patch as it is. If we don't hear otherwise, I propose sometime next week we queue Mark's patch for -next. -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [RFC PATCH 0/1] arm64: Fix /proc/cpuinfo Date: Thu, 6 Nov 2014 17:05:48 +0000 Message-ID: <20141106170548.GF19702@e104818-lin.cambridge.arm.com> References: <1414159000-27059-1-git-send-email-mark.rutland@arm.com> <20141106164311.GD19702@e104818-lin.cambridge.arm.com> <20141106165430.GH31605@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20141106165430.GH31605@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: Mark Rutland , "linux-arm-kernel@lists.infradead.org" , "ghackmann@google.com" , "ijc@hellion.org.uk" , Serban Constantinescu , "cross-distro@lists.linaro.org" , "linux-api@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: linux-api@vger.kernel.org On Thu, Nov 06, 2014 at 04:54:31PM +0000, Will Deacon wrote: > On Thu, Nov 06, 2014 at 04:43:12PM +0000, Catalin Marinas wrote: > > On Fri, Oct 24, 2014 at 02:56:39PM +0100, Mark Rutland wrote: > > > [d] Print different hwcaps dependent on the personality. > > > > > > This would allow for 32-bit and 64-bit applications to function > > > correctly, but for some 32-bit applications the personality would > > > need to be set explicitly by the user. > > > > Which makes this option actually in line with the uname -m behaviour. My > > vote goes for [d] with option [b] as a close alternative. > > > > > [1] arm, v3.17, Versatile Express A15x2 A7x3 coretile > > > Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm > > [...] > > > [2] arm64, v3.17, Juno platform > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 > > > > As an exercise, I'm trying to see what option [b] would look like when > > CONFIG_COMPAT is enabled: > > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae > > > > The duplicate strings would only be listed once (evtstrm, aes, pmull, > > sha1, sha2, crc32). New AArch64 features that we may expect to be > > optional on AArch32 could be prefixed with "a64". If they are missing > > entirely from AArch32, (like asimd), no need for the prefix. > > > > The advantage is that we don't need to check the personality but we have > > to assume that scripts would not search for substrings (sane people > > shouldn't do this anyway as the Features string can always be extended). > > And a big disadvantage is that I can imagine AArch64 applications checking > for "neon" instead of "asimd", which will break if they're run under kernels > without COMPAT support enabled. That's because they do stupid things and I they probably deserve to break ;). But I agree, there is a risk. > So I'm inclined to stick with Mark's patch as it is. If we don't hear otherwise, I propose sometime next week we queue Mark's patch for -next. -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Thu, 6 Nov 2014 17:05:48 +0000 Subject: [RFC PATCH 0/1] arm64: Fix /proc/cpuinfo In-Reply-To: <20141106165430.GH31605@arm.com> References: <1414159000-27059-1-git-send-email-mark.rutland@arm.com> <20141106164311.GD19702@e104818-lin.cambridge.arm.com> <20141106165430.GH31605@arm.com> Message-ID: <20141106170548.GF19702@e104818-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Nov 06, 2014 at 04:54:31PM +0000, Will Deacon wrote: > On Thu, Nov 06, 2014 at 04:43:12PM +0000, Catalin Marinas wrote: > > On Fri, Oct 24, 2014 at 02:56:39PM +0100, Mark Rutland wrote: > > > [d] Print different hwcaps dependent on the personality. > > > > > > This would allow for 32-bit and 64-bit applications to function > > > correctly, but for some 32-bit applications the personality would > > > need to be set explicitly by the user. > > > > Which makes this option actually in line with the uname -m behaviour. My > > vote goes for [d] with option [b] as a close alternative. > > > > > [1] arm, v3.17, Versatile Express A15x2 A7x3 coretile > > > Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm > > [...] > > > [2] arm64, v3.17, Juno platform > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 > > > > As an exercise, I'm trying to see what option [b] would look like when > > CONFIG_COMPAT is enabled: > > > > Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae > > > > The duplicate strings would only be listed once (evtstrm, aes, pmull, > > sha1, sha2, crc32). New AArch64 features that we may expect to be > > optional on AArch32 could be prefixed with "a64". If they are missing > > entirely from AArch32, (like asimd), no need for the prefix. > > > > The advantage is that we don't need to check the personality but we have > > to assume that scripts would not search for substrings (sane people > > shouldn't do this anyway as the Features string can always be extended). > > And a big disadvantage is that I can imagine AArch64 applications checking > for "neon" instead of "asimd", which will break if they're run under kernels > without COMPAT support enabled. That's because they do stupid things and I they probably deserve to break ;). But I agree, there is a risk. > So I'm inclined to stick with Mark's patch as it is. If we don't hear otherwise, I propose sometime next week we queue Mark's patch for -next. -- Catalin