Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751244AbaJKCk6 (ORCPT ); Fri, 10 Oct 2014 22:40:58 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:46462 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750727AbaJKCk4 (ORCPT ); Fri, 10 Oct 2014 22:40:56 -0400 Message-ID: <543898AB.7060304@hurleysoftware.com> Date: Fri, 10 Oct 2014 22:40:43 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 MIME-Version: 1.0 To: Nathan Lynch , Russell King - ARM Linux CC: Felipe Balbi , Rik van Riel , "Paul E. McKenney" , Tony Lindgren , Linux USB Mailing List , Linux Kernel Mailing List , josh@joshtriplett.org, Rabin Vincent , Alan Stern , Johannes Weiner , Sasha Levin , Andrew Morton , Linux OMAP Mailing List , Linus Torvalds , Linux ARM Kernel Mailing List Subject: Re: RCU bug with v3.17-rc3 ? References: <20140905213216.GD5001@linux.vnet.ibm.com> <20141008171322.GH22688@saruman> <20141008175707.GI22688@saruman> <20141008212938.GP22688@saruman> <20141009160138.GA2396@cmpxchg.org> <20141009162656.GE16002@saruman> <20141009204101.GA25955@debian> <20141009204637.GE25729@saruman> <20141009210715.GH25729@saruman> <20141010135743.GB31348@saruman> <20141010162531.GL12379@n2100.arm.linux.org.uk> <54388B81.5020306@mentor.com> In-Reply-To: <54388B81.5020306@mentor.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Authenticated-User: 990527 peter@hurleysoftware.com X-MT-ID: 8FA290C2A27252AACF65DBC4A42F3CE3735FB2A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/10/2014 09:44 PM, Nathan Lynch wrote: > On 10/10/2014 11:25 AM, Russell King - ARM Linux wrote: >> >> Right, so GCC 4.8.{1,2} are totally unsuitable for kernel building (and >> it seems that this has been known about for some time.) > > Looking at http://gcc.gnu.org/PR58854 it seems that all 4.8.x for x < 3 > are affected, as well as 4.9.0. > >> We can blacklist these GCC versions quite easily. We already have GCC >> 3.3 blacklisted, and it's trivial to add others. I would want to include >> some proper details about the bug, just like the other existing entries >> we already have in asm-offsets.c, where we name the functions that the >> compiler is known to break where appropriate. > > Before blacklisting anything, it's worth considering that simple version > checks would break existing pre-4.8.3 compilers that have been patched > for PR58854. It looks like Yocto and Buildroot issued releases with > patched 4.8.2 compilers well before the (fixed) 4.8.3 release. I think > the most we can reasonably do without breaking some correctly-behaving > toolchains is to emit a warning. Providing a manual switch to override blacklisting is way more sane than a build warning that no one's looking at. -- 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/