Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S947310AbdDTTxZ (ORCPT ); Thu, 20 Apr 2017 15:53:25 -0400 Received: from mail-io0-f181.google.com ([209.85.223.181]:34033 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031506AbdDTTwU (ORCPT ); Thu, 20 Apr 2017 15:52:20 -0400 MIME-Version: 1.0 In-Reply-To: References: <20161216105634.235457-1-arnd@arndb.de> <3302470.IDcDrWa0u6@wuerfel> From: Kees Cook Date: Thu, 20 Apr 2017 12:52:18 -0700 X-Google-Sender-Auth: JDz2I-kLE_i2TkgvuveKLX3E6X8 Message-ID: Subject: Re: [RFC] minimum gcc version for kernel: raise to gcc-4.3 or 4.6? To: Arnd Bergmann Cc: linux-arch , linux-kbuild , LKML , "linux-arm-kernel@lists.infradead.org" , Russell King , Andrew Morton , kernel-build-reports@lists.linaro.org, kvmarm@lists.cs.columbia.edu Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1467 Lines: 34 On Thu, Apr 20, 2017 at 3:15 AM, Arnd Bergmann wrote: > On Sun, Apr 16, 2017 at 9:52 PM, Kees Cook wrote: >>>> The original gcc-4.3 release was in early 2008. If we decide to still >>>> support that, we probably want the first 10 quirks in this series, >>>> while gcc-4.6 (released in 2011) requires none of them. >> >> I'd be in support of raising the minimum to gcc 4.6. (I'd actually >> prefer 4.7, just to avoid some 4.6 packaging issues, and for better >> gcc plugin support.) >> >> I'm curious what gcc 4.6 binaries are common in the wild besides >> old-stable Debian (unsupported in maybe a year from now?) and 12.04 >> Ubuntu (going fully unsupported in 2 weeks). It looks like 4.6 was >> used only in Fedora 15 and 16 (both EOL). > > I think we are better off defining two versions: One that we know > a lot of people care about, and we actively try to make that work > well in all configurations (e.g. 4.6, 4.7 or 4.8), fixing all warnings > we run into, and an older version that we try not to break > intentionally (e.g. 3.4, 4.1 or 4.3) but that we only fix when > someone actually runs into a problem they can't work around > by upgrading to a more modern compiler. For "working well everywhere" I feel like 4.8 is the better of those three (I'd prefer 4.9). I think we should avoid 4.6 -- it seems not widely used. For an old compiler... yikes. 3.4 sounds insane to me. :) -Kees -- Kees Cook Pixel Security