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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 D6AF7C43382 for ; Wed, 26 Sep 2018 15:32:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A4172150D for ; Wed, 26 Sep 2018 15:32:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7A4172150D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728293AbeIZVqL convert rfc822-to-8bit (ORCPT ); Wed, 26 Sep 2018 17:46:11 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:49899 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727250AbeIZVqL (ORCPT ); Wed, 26 Sep 2018 17:46:11 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1g5Bni-0001nJ-8c; Wed, 26 Sep 2018 17:32:30 +0200 Date: Wed, 26 Sep 2018 17:32:30 +0200 From: Sebastian Andrzej Siewior To: Bryan O'Donoghue , Denys Vlasenko , Ong@linutronix.de, Boon Leong Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" , Rik van Riel , Andy Lutomirski Subject: Re: [RFC PATCH 10/10] x86/fpu: defer FPU state load until return to userspace Message-ID: <20180926153229.n5rwlfhuqu42ds6v@linutronix.de> References: <20180912133353.20595-1-bigeasy@linutronix.de> <20180912133353.20595-11-bigeasy@linutronix.de> <650FC457-7E4C-473A-9E5F-EAFC74F6444B@amacapital.net> <20180919170515.ptqmmpsxrdjsi64j@linutronix.de> <20180926111222.hihueuagmb4qfmtz@linutronix.de> <59E2EBC5-C483-4788-B490-4A3770DBB993@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <59E2EBC5-C483-4788-B490-4A3770DBB993@amacapital.net> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-09-26 07:34:09 [-0700], Andy Lutomirski wrote: > > So I *think* nobody relies on FPU-emulation anymore. I would suggest to > > get this patch set into shape and then getting rid of > > CONFIG_MATH_EMULATION? Bryan, Denys, does anyone of you rely on CONFIG_MATH_EMULATION? The manual for Quark claims that the CPU has no FPU and yet the current kernel (or the yocto v3.14) does not select this option. Denys added support for some opcodes in 2015 but I didn't figure out *why* or which CPU in particular requires this. > I don’t think you can boot a kernel without math emulation on a no-FPU CPU. So maybe we should table this particular idea. I didn’t realize there were Quark CPUs without FPU. Okay. Sebastian