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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 E9277C282CB for ; Tue, 5 Feb 2019 08:49:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B64452080F for ; Tue, 5 Feb 2019 08:49:15 +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="oI6z5eKt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727969AbfBEItO (ORCPT ); Tue, 5 Feb 2019 03:49:14 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44128 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725898AbfBEItN (ORCPT ); Tue, 5 Feb 2019 03:49:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=KYXzUg2sSAEXhCe7Oa4aiko3S0J1+A60eyUxbL/J5bc=; b=oI6z5eKt7n6KoEuuEZsmUm46R OQ5R3Us7nZaPGXm/ruAMDgl5lgeVcCPH/Hs4ITH50DaW6gwfcHe3XUtWNsrEW1fY5vAyHHSCc4exf 2mqQ/yijjvCZC1cg5Hr2hrJQoyyrdOQrDh78LN5m4CR5fhv7cpy7XBaIm4Wz2OJHmpnY/7VNNL9mG kT4bDQG0LJ9st60SYNzfxBtuZIJukBxx4QvET9BDQQHIrdpxedq7jana2aAv2ENVvt+1gBNohxFBa aWinby4PVneonb+Nf8hWajbyzebCqob+8sZLy2f0Wbj6N7L17SQ6XPW7F7nysOuqucVpj3AenO79d ObvEX/Gbw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gqwPc-00021Q-6G; Tue, 05 Feb 2019 08:49:00 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AB7AB2029FA06; Tue, 5 Feb 2019 09:48:57 +0100 (CET) Date: Tue, 5 Feb 2019 09:48:57 +0100 From: Peter Zijlstra To: Dave Hansen Cc: Borislav Petkov , Thomas Gleixner , Fenghua Yu , Ingo Molnar , H Peter Anvin , Ashok Raj , Michael Chan , Ravi V Shankar , Ricardo Neri , linux-kernel , x86 Subject: Re: [PATCH v3 08/10] x86/setcpuid: Add kernel option setcpuid Message-ID: <20190205084857.GK17528@hirez.programming.kicks-ass.net> References: <1549084491-57808-1-git-send-email-fenghua.yu@intel.com> <1549084491-57808-9-git-send-email-fenghua.yu@intel.com> <9fa7406b-113f-fe0a-9fc7-ef00b3a6b620@intel.com> <20190204195704.GJ29639@zn.tnic> <5c2f0af3-1740-f16b-6ff6-6bec6a325034@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5c2f0af3-1740-f16b-6ff6-6bec6a325034@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 04, 2019 at 12:46:30PM -0800, Dave Hansen wrote: > So, the compromise we reached in this case is that Intel will fully > document the future silicon architecture, and then write the kernel > implementation to _that_. Then, for the weirdo deployments where this > feature is not enumerated, we have the setcpuid= to fake the enumeration > in software. What user is _EVER_ going to use this? Nobody, I expect the answer to be. Is this some transient state; where a few (early) models will not have the enumeration sorted but all later models will have it all neat and tidy? If so, we can easily do the FMS solution for this. But a cmdline features thing is not something I can see anybody but a limited set of developers ever using.