From owner-freebsd-current@FreeBSD.ORG Wed Feb 4 17:45:23 2015 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 766E7764 for ; Wed, 4 Feb 2015 17:45:23 +0000 (UTC) Received: from mail-qg0-x235.google.com (mail-qg0-x235.google.com [IPv6:2607:f8b0:400d:c04::235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2FC5EAE0 for ; Wed, 4 Feb 2015 17:45:23 +0000 (UTC) Received: by mail-qg0-f53.google.com with SMTP id f51so2332505qge.12 for ; Wed, 04 Feb 2015 09:45:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=SsRX0x/2d5uV2Sy0BZrTf2opiG1ETYxVJKG3C+LKZF4=; b=ufeCW6+Q35vMFRKzPXq/lq9EDqVLNxzCnALKwdoeOdIMr4QRPndCB6MiYnSPzbT8np pndA8KPkxfHTiEk156Ke+EjLNB9b/YJ4iNhlUXO9P05cZZB2gdK8IszByWhLW/FzQzsd 980ND0275KxWQg0JBm7apczLebHkwBH7XrSDwA/R3Ol2hIVEGVSt1lUiX94Ekccpn45F Et61giZ6w7QgJi2Ou+AZXIJo3FofdrGeqH2MCxw+1IEyHw1l3AC2YN8I5kowc3Jrt0Ub 59KhNKMFa9MwsiCMG9MySxwZ0+6Upa/uhzBzSZq358A8Z3tTiUeWlFT1a7MDNiKap6PQ 5Rjg== X-Received: by 10.140.37.39 with SMTP id q36mr61385070qgq.89.1423071921745; Wed, 04 Feb 2015 09:45:21 -0800 (PST) MIME-Version: 1.0 Sender: carpeddiem@gmail.com Received: by 10.140.39.209 with HTTP; Wed, 4 Feb 2015 09:45:00 -0800 (PST) In-Reply-To: <20150204142941.GE42409@kib.kiev.ua> References: <8089702.oYScRm8BTN@overcee.wemm.org> <20150204142941.GE42409@kib.kiev.ua> From: Ed Maste Date: Wed, 4 Feb 2015 12:45:00 -0500 X-Google-Sender-Auth: ZC_67nJh9spgCrBBje9HtNAtU4c Message-ID: Subject: Re: PSA: If you run -current, beware! To: Konstantin Belousov Content-Type: text/plain; charset=UTF-8 Cc: freebsd-current , Peter Wemm X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Feb 2015 17:45:23 -0000 On 4 February 2015 at 09:29, Konstantin Belousov wrote: > > So the issue is reproducable in 3 minutes after boot with the following > change in kern_clock.c: > volatile int ticks = INT_MAX - (/*hz*/1000 * 3 * 60); > > It is fixed (in the proper meaning of the word, not like worked around, > covered by paper) by the patch at the end of the mail. > > We already have a story trying to enable much less ambitious option > -fno-strict-overflow, see r259045 and the revert in r259422. Note that -fno-strict-overflow and -fwrapv are equivalent as far as Clang is concerned: | // -fno-strict-overflow implies -fwrapv if it isn't disabled, but | // -fstrict-overflow won't turn off an explicitly enabled -fwrapv. | if (Arg *A = Args.getLastArg(options::OPT_fwrapv, | options::OPT_fno_wrapv)) { | if (A->getOption().matches(options::OPT_fwrapv)) | CmdArgs.push_back("-fwrapv"); | } else if (Arg *A = Args.getLastArg(options::OPT_fstrict_overflow, | options::OPT_fno_strict_overflow)) { | if (A->getOption().matches(options::OPT_fno_strict_overflow)) | CmdArgs.push_back("-fwrapv"); | } > I do not see other way than try one more time. Agreed. As you noted elsewhere the original issue that triggered the revert was fixed by r259609, so we should be able to just re-apply r259045.