From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C0C7A2A; Mon, 22 Jan 2024 02:05:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705889108; cv=none; b=RoNT+tLeuW6MZa8ZhIEuvPByJ1PxN8KTeZWN6OM36LZAer6S9cazay49vVO4/ciZsNMvRCp9ZaTa9fYUGrsEtYKeg2TJz854UMIosqSwDcScfdtN6WAgP/eUvB3lOwHoznXeGJ70eXdHNPql5RSvhq0lkgfdyy3oFwacVaUxuc0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705889108; c=relaxed/simple; bh=MBeI8qR+plUgYcOOi7evJyai63+yRXkp1o/8PBJugnE=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=kuf5qWqpsSXacL9ywrYwbN8LGSyCIsRGgeN2ThUYXedlIR0yGFXGrcoebg6GWiJWL5rhArRH838CYFGlSQsFSk3r0M+llK5/Vtt+3Guu39nrw2M7En364WTb6P7DVYP+b/Y5Yb3q30DyORDedC/rXCtz+UcuUDeMqnj1uESY4AY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=Qe+iX8JU; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="Qe+iX8JU" Received: from [127.0.0.1] ([76.133.66.138]) (authenticated bits=0) by mail.zytor.com (8.17.2/8.17.1) with ESMTPSA id 40M24iJx2289796 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Sun, 21 Jan 2024 18:04:44 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 40M24iJx2289796 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2024011201; t=1705889085; bh=MBeI8qR+plUgYcOOi7evJyai63+yRXkp1o/8PBJugnE=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=Qe+iX8JUPN8aKdw+N6qIhojZMwylgtzACi5j2EQLmeu1d6WmqQ/354Rkrq6orwdNt t6E6mqqrjcYblA1wrrGxORhQgpvzdXTI/dQa+t6I6VqXUNsU/qvaav7OFD8cs0+mpP bWqjLLZufwJfl31en+tqIIQ2kDWjXl7UTpSSEXXF5xc/fmjFdM5MmCAaOYmDQnlJl8 6Xt7sd94Wm9kPWlKGZEdlp5MWphWV8iNBt+8p5PF19vPNeIv7ZfC24I70zmFAf9WF0 AZOx+DFGgJeSFDrU2k8xYpikcCrXvfMZUzS9eqx9DUGB7qsLnm05zOEAiu9apwFd2s dF8cEddBKFrUA== Date: Sun, 21 Jan 2024 18:04:42 -0800 From: "H. Peter Anvin" To: Thorsten Glaser , Steven Rostedt CC: Peter Zijlstra , x86@kernel.org, torvalds@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-toolchains@vger.kernel.org, jpoimboe@redhat.com, alexei.starovoitov@gmail.com, mhiramat@kernel.org Subject: Re: [PATCH 1/2] x86: Remove dynamic NOP selection User-Agent: K-9 Mail for Android In-Reply-To: References: <20210312113253.305040674@infradead.org> <20210312115749.065275711@infradead.org> <20B57BDC-9A3F-4B02-9BA9-41477088A6CE@zytor.com> <20240121195649.7355e1d5@rorschach.local.home> Message-ID: <4F17FAD6-9183-4F29-850D-8DE88FAB3658@zytor.com> Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On January 21, 2024 5:17:36 PM PST, Thorsten Glaser wrote= : >Steven Rostedt dixit: > >>> >This was, incidentally, triggered by looking into a problem report th= at >>> >something did *not* work on a Geode LX system=2E >> >>What problem happened? > >It turned out to be a compiler issue (GCC thinks i686 means PPro, >not 686-class CPUs, and -fcf-protection causes long NOPs, which >not all 686-class CPUs support, to be inserted)=2E This turned out >to break a large part of Debian stable on OLPCs and other systems, >and the kernel=E2=80=99s changes in nopl handling were tabled as argument= s=2E > >https://www=2Ejookia=2Eorg/wiki/Nopl has a longer writeup on the nopl >history=2E > >bye, >//mirabilos i686 *is* Pentium Pro=2E=2E=2E