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=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 39365C433DB for ; Wed, 23 Dec 2020 18:38:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F10932229C for ; Wed, 23 Dec 2020 18:38:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728099AbgLWSil (ORCPT ); Wed, 23 Dec 2020 13:38:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726923AbgLWSil (ORCPT ); Wed, 23 Dec 2020 13:38:41 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2357C061794; Wed, 23 Dec 2020 10:38:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description; bh=2/PotIte2uF8Rp7Cxfp8eiOJ3+42/nTavyU1PczDiAY=; b=hJlntF1PVWHo/AFsU4PjBe0Axn 5dl2/TaR8pr6w/owzLDYXGOIiipRHHvQb7P7328s0OziQDAF5kthOlgP3RTG1EzFfMbTes/n1C8EC rJbLJh1VWaobbTUUt+Gm1XBLDYycB1PK3Zk5kP42MmGFPMoAi+QsRHW34XRw5vDqoQ9JyumAd0+nr XGo49aha8fL3+IiFOoQkMBGuSsp7bTiWarMnCKee4iKJOXBK6xZamgWm/sEI+JS2TZkntq2+ZpWqI 3xg/1aMmUy/4qKY/C1az2IJliNqFsEuVKBAyNmYdwABJ9JESgPF5mU3Z7uuLfSX4ADi75syOoy0ts ehfI1Lsw==; Received: from [2601:1c0:6280:3f0::64ea] by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ks91J-0003Mc-HD; Wed, 23 Dec 2020 18:37:57 +0000 Subject: Re: [PATCH v3 21/21] x86/fpu/xstate: Introduce boot-parameters to control some state component support To: "Chang S. Bae" , bp@suse.de, luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, x86@kernel.org Cc: len.brown@intel.com, dave.hansen@intel.com, jing2.liu@intel.com, ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org References: <20201223155717.19556-1-chang.seok.bae@intel.com> <20201223155717.19556-22-chang.seok.bae@intel.com> From: Randy Dunlap Message-ID: <64c67e40-ecba-5d9b-7c4b-4c64ea62906a@infradead.org> Date: Wed, 23 Dec 2020 10:37:52 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201223155717.19556-22-chang.seok.bae@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/23/20 7:57 AM, Chang S. Bae wrote: > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 44fde25bb221..a67ae04d43c5 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6002,6 +6002,21 @@ > which allow the hypervisor to 'idle' the guest on lock > contention. > > + xstate.enable= [X86-64] > + xstate.disable= [X86-64] > + The kernel is compiled with a default xstate bitmask -- > + enabling it to use the XSAVE hardware to efficiently > + save and restore thread states on context switch. > + xstate.enable allows adding to that default mask at > + boot-time without recompiling the kernel just to support > + the new thread state. (Note that the kernel will ignore > + any bits in the mask that do not correspond to features > + that are actually available in CPUID) xstate.disable CPUID.) > + allows clearing bits in the default mask, forcing the > + kernel to forget that it supports the specified thread > + state. When a bit set for both, the kernel takes > + xstate.disable in a priority. as a priority. ? thanks. -- ~Randy