From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932300AbcHKUaV (ORCPT ); Thu, 11 Aug 2016 16:30:21 -0400 Received: from mout.kundenserver.de ([217.72.192.75]:64596 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932129AbcHKUaT (ORCPT ); Thu, 11 Aug 2016 16:30:19 -0400 From: Arnd Bergmann To: Catalin Marinas Cc: "Zhangjian (Bamvor)" , Yury Norov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, libc-alpha@sourceware.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, pinskia@gmail.com, broonie@kernel.org, joseph@codesourcery.com, christoph.muellner@theobroma-systems.com, szabolcs.nagy@arm.com, klimov.linux@gmail.com, Nathan_Lynch@mentor.com, agraf@suse.de, Prasun.Kapoor@caviumnetworks.com, kilobyte@angband.pl, geert@linux-m68k.org, philipp.tomsich@theobroma-systems.com, manuel.montezelo@gmail.com, linyongting@huawei.com, maxim.kuvyrkov@linaro.org, davem@davemloft.net, Andrew Pinski , Andrew Pinski , Bamvor Jian Zhang , Hanjun Guo Subject: Re: [PATCH 05/19] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Date: Thu, 11 Aug 2016 22:29:03 +0200 Message-ID: <2034620.lN3lAEBAXs@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-31-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <20160811163003.GD18366@e104818-lin.cambridge.arm.com> References: <1466207668-10549-1-git-send-email-ynorov@caviumnetworks.com> <6457502.FRufylo3sd@wuerfel> <20160811163003.GD18366@e104818-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:YoIRZeM2dB0gIx6kqrZU36u5iCZVsMSK4wxcT3uZDr5CF2P9leg RofksIWdaI2dLeeUmNrWBfglLoTPxpHzKucbUHIT9fv4Z5hIM/NLQY9Bp40S1MSTG9azn66 o04+PYNSYwbQQym0LeB5QgLIUhT4ejpPg8xR8maL8mLC8yQ46wRjPqhMUxMAIQbI35BnIa5 UcixYCf6UwIKzsUAeLUoQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:GP1SIlUZgoc=:wVKYnsiGGE92o8GcndeIXl SXDugk9qfFi8jVBRCHbTrFq3q8CRA8gDwXUdpfSHRaOA5OqA2UFCIuxO33LgbY2V3PZNm9ai5 5eY3Z6n9Zp07S90h6frDpydSdMU5Vy9V7k/s0OeiWNCZqK4YQvP+9dz7q0aPLSnMVzSSJYRwC kBt0yZifgtIg2Iizeaof2DpjWqG2uaPxlCKl8S6+rkRmNu8Gug9GRxsafeU1HppxNbxpEqySD XjCPMJTuwoex21msXQIflY7XpJ6+1L5nxAp3arV4P1jaLQQMW4CM3S7rAo7g9jr0kIBq5RlBm iQ9xvYNYj7zBLJxv15KrXbnDqkMN17keIhIrzhu3k8Cgd/e3iVLK6W8LxRgpIJ/lKBhJZH9x1 /zLQf5yyuXBqdimJY/SApqg8JwWOSVxPSk/NndoUEsyQruJYOHfMY8UBMXqxU098qBhg/A1Ww lUIfngLtqzKgvMAewbGbv27S27KDa3JsIMCHlHR+xaTYKgexCfol1ev+Uw6uDAbSIF6rci9nh R1GwiUrfu/kSJ/F8v+FnfHMeXeJKff7Wc5NcCNs93WXYh4rOfL5qcZyQ+5re3kovyjBW9auyM byTmAVX3DHwT0cIzvlye5DKKTMbSD7bhr5KG/yi2UnOkbLm0WsuC1EnUCtPsg/5gLpZVaqMcF cm/QVJ+Lr5/ibK8yWd/Xoj3yrS4xs8etxr2nldCBFcE1AyeXDZQPLx+8ANDc/CYmRzpmIy6NN 1mWLK8pm6Uo0yLU7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, August 11, 2016 5:30:03 PM CEST Catalin Marinas wrote: > > > > and you can have ARM binaries with > > > > PER_LINUX (using the arm64 uname) just like you can have > > > > arm64 binaries running with PER_LINUX32. > > > > > > I was actually looking to enforce the 32-bit binaries to only see > > > PER_LINUX32, though with a risk of breaking the ABI. OTOH, people are > > > abusing this and write 32-bit apps relying on the 64-bit /proc/cpuinfo: > > > > > > http://lkml.kernel.org/g/1464706504-25224-3-git-send-email-catalin.marinas@arm.com > > > > > > (you were summoned on that discussion couple of times ;)) > > > > Hmm, I thought I saw the thread and didn't have any good idea for > > the uname information, but didn't notice it was for /proc/cpuinfo. > > > > What's wrong with always showing both the 32-bit and the 64-bit > > hwcap strings here (minus the duplicates, which hopefully have > > the same meaning here)? > > As I said above, some of them have the same name (which may be a good > thing at a first look) but we don't have an architecture guarantee that > the feature is present in both AArch32 and AArch64 modes (e.g. AES may > only be available in AArch64). Is this the case on actual implementations that exist today? If they are actually always both present, we might be able to get away with it. Arnd