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 6125EC73C7C for ; Wed, 10 Jul 2019 08:23:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2481820844 for ; Wed, 10 Jul 2019 08:23:47 +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="ItYNfLB/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727412AbfGJIXp (ORCPT ); Wed, 10 Jul 2019 04:23:45 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:44106 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726097AbfGJIXp (ORCPT ); Wed, 10 Jul 2019 04:23:45 -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=KHsCceUwFj0VCBCJ1Vn7vA7gOHS6l0320ELVzrYcy0s=; b=ItYNfLB/DBiyNIjWV16Va8Z1f Fs9GQxDleXj1+NXT7leCxwbEop+GSMzry4rYr2+vRFeDNGvbaANfdKR7cOiHACIpGi7caj50WqLBl K3/YuUwW3hWGeBzzSDwevFMfkuJef4r2awS5mR0Ze8tCsYJF2UURZQF99paE8Hp8ssBgJQRNJId+k JlQenguNGzCYWSIrER9udcRetVnztBSUWq5oDr+6ChDphkOaJkEev4rlRhrJAA3VjeKvLsrQ7U3O2 ZipWkDIUtDJLqQmwvikvie6Y8nenzzue5nCGMMRE+HW8uRp65CBNhZKYRaQFfS7+wyAYurC+XLUKN 6kcufbp8w==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:59328) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hl7t3-0005Zi-VT; Wed, 10 Jul 2019 09:23:38 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1hl7t1-0003km-Hp; Wed, 10 Jul 2019 09:23:35 +0100 Date: Wed, 10 Jul 2019 09:23:35 +0100 From: Russell King - ARM Linux admin To: Masahiro Yamada Cc: linux-arm-kernel , Olof Johansson , Arnd Bergmann , Linux Kernel Mailing List , masahiroy@kernel.org Subject: Re: Question about ARM FASTFPE Message-ID: <20190710082335.uzusesefimzpjd3f@shell.armlinux.org.uk> References: 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 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. > and the actual source code for arch/arm/fastfpe/ > was never upstreamed. > > > In general, we do not care much about the downstream code support. > > What should we do about this? > Fix and keep maintaining? Delete? > > > -- > Best Regards > Masahiro Yamada > -- 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