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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 A8213C433E7 for ; Wed, 2 Sep 2020 16:45:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D73E207EA for ; Wed, 2 Sep 2020 16:45:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="o0p4+Jbo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727101AbgIBQp5 (ORCPT ); Wed, 2 Sep 2020 12:45:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbgIBQp5 (ORCPT ); Wed, 2 Sep 2020 12:45:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4D9AC061244 for ; Wed, 2 Sep 2020 09:45:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KlqdMA9Ymkva2L993Ie06kUO8p+MwX4KAMlWqqYhqi8=; b=o0p4+JboOuQwfd5Df12KScy2MD +nAvnnMkAe7FA7Y6DGSqL2pqAcDunGGH0vyvdJMESv+TYPEQUcLpYi9pO7iC82L/HhNOBgZJnBogf D4xCnI/s6vCIJIL4E3m9v7fieRWrBZB46AEHKUjINYiVTkkLxy+pAmjfXkjoUcdGX7E4vXDc6KOR8 Iki3Jgkn3ubyGcSqf/z1tMYDqtCJJT7NZWo5oM4h8A6q6eGcykHo6QoFUOEHTsPPRGVQhYy19IeE1 BPrH8OXTmi0MUa1o7a/HwOP5+lmGcEcjt2QKj3sJAF9nvxbgibgvumc7ax8LFzzSq3zzIIRhcvCrG wZClltzQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDVtF-0008J6-RQ; Wed, 02 Sep 2020 16:45:42 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 89AC03011C6; Wed, 2 Sep 2020 18:45:38 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 73B662C580820; Wed, 2 Sep 2020 18:45:38 +0200 (CEST) Date: Wed, 2 Sep 2020 18:45:38 +0200 From: peterz@infradead.org To: Feng Tang Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Borislav Petkov , Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] tools/x86: add kcpuid tool to show raw CPU features Message-ID: <20200902164538.GN1362448@hirez.programming.kicks-ass.net> References: <1598514543-90152-1-git-send-email-feng.tang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1598514543-90152-1-git-send-email-feng.tang@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 27, 2020 at 03:49:03PM +0800, Feng Tang wrote: > End users frequently want to know what features their processor > supports, independent of what the kernel supports. > > /proc/cpuinfo is great. It is omnipresent and since it is provided by > the kernel it is always as up to date as the kernel. But, it can be > ambiguous about processor features which can be disabled by the kernel > at boot-time or compile-time. Let me once again suggest we use CPUID faulting to 'fix' this. We really should clear the CPUID bits when the kernel explicitly disables things. https://lkml.kernel.org/r/1552431636-31511-18-git-send-email-fenghua.yu@intel.com