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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 8C670C004EF for ; Wed, 10 Jul 2019 10:46:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F67B2064A for ; Wed, 10 Jul 2019 10:46:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="Lb8OPWRR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727386AbfGJKqf (ORCPT ); Wed, 10 Jul 2019 06:46:35 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:45866 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbfGJKqe (ORCPT ); Wed, 10 Jul 2019 06:46:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: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=jvMZpPPrD/tSFkNyX/FfJWti0dh2u8MlHDBE38NmrZQ=; b=Lb8OPWRRj9rcMiZ8SIEM/9MnV EVogylyL2oO9c6HyXAl3XNcVpDjhqVahYg5Wo32pWa0ksOqSKPWY4rIGXj3XWm0yY6YQU2Ak9DD89 LM6tHs0zQfSGnUogfZhpQY77Y7RD64o1m6XCXZtzVq1g0jKnSt4ijyx9WlyrOFmnie0zKBWaaqd3K 9hD6O59yc+ilHFCj3l+tu0JFbKN2jCc71dQ8+vjN0gRHJXD5aUvbMrqTuvZtOfGTfm/25tT2Tr+ZB +WET8Yka2YhKze87KCQplyslmm6onP0p4r9u6C4wm+fZPkVPGYi/yQTEh3gADupUEmyif0wvHCtAT 6/m+yZhXg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:60336) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hlA7I-0006BT-R5; Wed, 10 Jul 2019 11:46:28 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1hlA7H-0003qR-Af; Wed, 10 Jul 2019 11:46:27 +0100 Date: Wed, 10 Jul 2019 11:46:27 +0100 From: Russell King - ARM Linux admin To: Masahiro Yamada Cc: linux-arm-kernel , Olof Johansson , Arnd Bergmann , Linux Kernel Mailing List Subject: Re: Question about ARM FASTFPE Message-ID: <20190710104627.5lam7ipqljks3iji@shell.armlinux.org.uk> References: <20190710082335.uzusesefimzpjd3f@shell.armlinux.org.uk> <20190710100206.yls4piu36wciefbz@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 10, 2019 at 07:43:19PM +0900, Masahiro Yamada wrote: > On Wed, Jul 10, 2019 at 7:02 PM Russell King - ARM Linux admin > wrote: > > > > On Wed, Jul 10, 2019 at 06:54:06PM +0900, Masahiro Yamada wrote: > > > On Wed, Jul 10, 2019 at 5:23 PM Russell King - ARM Linux admin > > > wrote: > > > > > > > > On Wed, Jul 10, 2019 at 01:30:24PM +0900, Masahiro Yamada wrote: > > > > > Hi. > > > > > > > > > > I have a question about the following code > > > > > in arch/arm/Makefile: > > > > > > > > > > > > > > > # Do we have FASTFPE? > > > > > FASTFPE :=arch/arm/fastfpe > > > > > ifeq ($(FASTFPE),$(wildcard $(FASTFPE))) > > > > > FASTFPE_OBJ :=$(FASTFPE)/ > > > > > endif > > > > > > > > > > > > > > > Since arch/arm/fastfpe does not exist in the upstream tree, > > > > > I guess this is a hook to compile downstream source code. > > > > > > > > > > If a user puts arch/arm/fastfpe/ into their local source tree, > > > > > Kbuild is supposed to compile the files in it. > > > > > > > > > > Is this correct? > > > > > > > > > > > > > > > If so, I am afraid this would not work for O= building. > > > > > > > > > > $(wildcard ...) checks if this directory exists in the *objtree*, > > > > > while scripts/Makefile.build needs to include > > > > > arch/arm/fastfpe/Makefile from *srctree*. > > > > > > > > > > I think the correct code should be like follows: > > > > > > > > > > # Do we have FASTFPE? > > > > > FASTFPE :=arch/arm/fastfpe > > > > > ifneq ($(wildcard $(srctree)/$(FASTFPE)),) > > > > > FASTFPE_OBJ :=$(FASTFPE)/ > > > > > endif > > > > > > > > > > > > > > > Having said that, I am not sure this code is worth fixing. > > > > > > > > > > This code was added around v2.5.1.9, > > > > > > > > ... as a _result_ of a discussion and deciding not to upstream it, > > > > but to still allow its use. Fastfpe is faster than nwfpe (so has > > > > a definite advantage for FP intensive applications) but we decided > > > > we didn't want two FP emulation codes in the kernel. However, if > > > > someone wants to use it, it has to be built into the kernel, it > > > > can't be modular. > > > > > > > > > IMHO, the entry in Makefile and Kconfig should be removed > > > from upstream, then moved to a part of the fastfpe local patch. > > > > Nope. It means that rather than it being merely a drop-in, it has > > to be maintained against changes to both these files. Sorry, that's > > more work. > > > This is the motivation of upstreaming for everybody. > > We never know the code that does not exist in upstream. > Downstream code must pay maintenance cost for ever. I'm the maintainer of the files in question. I also care-take fastfpe. It's my choice to make. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up