From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DBE2C282DD for ; Wed, 17 Apr 2019 23:55:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D73621479 for ; Wed, 17 Apr 2019 23:55:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387768AbfDQXz2 (ORCPT ); Wed, 17 Apr 2019 19:55:28 -0400 Received: from mga11.intel.com ([192.55.52.93]:2215 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729331AbfDQXz1 (ORCPT ); Wed, 17 Apr 2019 19:55:27 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Apr 2019 16:55:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,363,1549958400"; d="scan'208";a="162854450" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by fmsmga004.fm.intel.com with ESMTP; 17 Apr 2019 16:55:27 -0700 Date: Wed, 17 Apr 2019 16:47:28 -0700 From: Fenghua Yu To: Thomas Gleixner Cc: Ingo Molnar , Borislav Petkov , H Peter Anvin , Paolo Bonzini , Dave Hansen , Ashok Raj , Peter Zijlstra , Ravi V Shankar , Xiaoyao Li , Christopherson Sean J , Kalle Valo , Michael Chan , linux-kernel , x86 , kvm@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH v7 18/21] x86/clearcpuid: Support feature flag string in kernel option clearcpuid Message-ID: <20190417234728.GA18776@romley-ivt3.sc.intel.com> References: <1555536851-17462-1-git-send-email-fenghua.yu@intel.com> <1555536851-17462-19-git-send-email-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thu, Apr 18, 2019 at 01:19:41AM +0200, Thomas Gleixner wrote: > On Wed, 17 Apr 2019, Fenghua Yu wrote: > > > The kernel option clearcpuid currently only takes feature bit which > > can be changed from kernel to kernel. > > > > Extend clearcpuid to use cap flag string, which is defined in > > x86_cap_flags[] and won't be changed from kernel to kernel. > > And user can easily get the cap flag string from /proc/cpuinfo. > > If your machine dies because init triggers #AC then please explain how that > easily can be read from /proc/cpuinfo and how the sysadmin can figure out > what the heck he needs to write on the kernel command line. > > The whole 'clearcpuid' thing should have never been merged. It's a pure > testing/debugging thing. And no, we are not going to proliferate it and > extend it for dubious value. Quite the contrary, we should simply rip it > out. So I can remove the four 'clearcpuid' related patches 0018-0021 in the next version, right? > > Add a simple 'noac' or whatever command line option, which is documented > proper and can easily be mapped to a #AC crash during boot. OK. I will do this. Thanks. -Fenghua