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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B9CE2C433DB for ; Mon, 18 Jan 2021 12:23:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69DFF2065E for ; Mon, 18 Jan 2021 12:23:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390474AbhARMXq (ORCPT ); Mon, 18 Jan 2021 07:23:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391196AbhARMW2 (ORCPT ); Mon, 18 Jan 2021 07:22:28 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8DC6C061573 for ; Mon, 18 Jan 2021 04:21:47 -0800 (PST) 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=icRNAkK0szBBjqq/5Vje/Fh2SCFts7ZENzZRRvbWGz8=; b=tbic5vIrHaPdWR83ygRvHMuxWa z0VUx/9IC9FnTQzv0B8OJ9vsmvMWn28fj7RyGYAeAsHr5UYpvbJmwkm21MgzIGrxXhrCUGWJpUaKq Aa6Ehl2Z/l2h+r61EHVdetB6eh44sPxCC1705IukbuvbBYgHZBZBKdGbmMgqnPPxyDNDiMfRgTvoq OoZVqpRJVOhHDfWWTmZe6Ju9dRN+I4/SKdCEBsTE82KMmxheZCc4GtmA1M6cQPQzC+8iRXAjP26nO Gc9moMo4MpUub6s4aCjdK7rcypZS6aAwL092JcI5+wwWPTP0My0lkWQ+z26EdrAw2VAOG3kUJwbs/ PE5LuESg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l1TXK-00CnRY-L3; Mon, 18 Jan 2021 12:21:35 +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 33C1D30015A; Mon, 18 Jan 2021 13:21:32 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1B79220290D25; Mon, 18 Jan 2021 13:21:32 +0100 (CET) Date: Mon, 18 Jan 2021 13:21:32 +0100 From: Peter Zijlstra To: Andy Lutomirski Cc: x86@kernel.org, LKML , Krzysztof Mazur , Krzysztof =?utf-8?Q?Ol=C4=99dzki?= , Arnd Bergmann Subject: Re: [PATCH 1/4] x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize state Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 17, 2021 at 10:20:38PM -0800, Andy Lutomirski wrote: > - Code that wants MMX doesn't want need MXCSR or FCW initialized. > _mmx_memcpy(), for example, can run before CR4.OSFXSR gets set, and > initializing MXCSR will fail. > +#define KFPU_MMX 0 /* nothing gets initialized */ This... why is that correct?