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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C66ABC7EE2F for ; Mon, 12 Jun 2023 15:27:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=dDwdvsfhye1W7j5Rb5RXusy5Cftc0LXT3Gjzddi86o0=; b=dwDkc4vMe1JMpn /DYoFyvwV3JscEKe8gzKKx6LaoOjel0xOxom6snBpg8OfT+sPtudAA+RNp/hJ10qDKgu3DvXcudow pIkR3sJjCwXWLYlYvK/7WSjDxa+G/NUXEu/3M4VepRdEhPL0iC5KZ4HQMDHI/KG/bK+86LVCg+YFx HGjNzrvM+plunxnJBGm3ZXfATAjK91oMbli0GRJFpkjeYG4jTeXnT6XNqjhRufxWDNl68CW/oRkJm LAiR0RPzH7ucw5I8tTqJz/J7Z40DEiq3ozS4EKPmFeYscM1QPUezzl6t9bbhqM32KufT4kdkfdbxs oqonel+PuP9UuYaDenmQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q8jRk-004Ta9-04; Mon, 12 Jun 2023 15:27:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q8jRh-004TZP-0v for linux-arm-kernel@lists.infradead.org; Mon, 12 Jun 2023 15:27:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 740431FB; Mon, 12 Jun 2023 08:27:47 -0700 (PDT) Received: from capper-ampere.manchester.arm.com (capper-ampere.manchester.arm.com [10.32.100.23]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0D71F3F5A1; Mon, 12 Jun 2023 08:27:00 -0700 (PDT) From: Jamie Cunliffe To: boqun.feng@gmail.com Cc: Jamie.Cunliffe@arm.com, catalin.marinas@arm.com, lina@asahilina.net, linux-arm-kernel@lists.infradead.org, ojeda@kernel.org, rust-for-linux@vger.kernel.org, steve.capper@arm.com, will@kernel.org Subject: Re: [PATCH v2 1/3] arm64: rust: Enable Rust support for AArch64 Date: Mon, 12 Jun 2023 16:26:39 +0100 Message-Id: <20230612152639.1446766-1-Jamie.Cunliffe@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230612_082705_390613_91554FBB X-CRM114-Status: GOOD ( 11.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > I don't think you need "-fp-armv8" here, because "aarch64-unknown-none" > target doesn't have the target-feature "fp-arm64": > > rustc +1.68.2 --print cfg --target aarch64-unknown-none | grep target_feature > > target_feature="neon" > > , and having the "-fp-armv8" gave me a warning at compile time: > > RUSTC L rust/core.o warning: unknown feature specified for `-Ctarget-feature`: `fp-armv8` > | > = note: it is still passed through to the codegen backend > = help: consider filing a feature request Rust removed the fp feature for arm64 and tied it with Neon. However this initially had a bug that meant it couldn't be disabled. This has now been fixed in https://github.com/rust-lang/rust/pull/107294 so once we can update rustc we can fix that warning by removing the `-fp-armv8`. Until we do that we still need the `-fp-armv8` otherwise we will get some floating point usage. This can be seen by doing an objdump of core.o if you build after removing the `-fp-armv8`. You can also see that fp-armv8 is enabled in the aarch64-unknown-none target here: https://raw.githubusercontent.com/rust-lang/rust/master/compiler/rustc_target/src/spec/aarch64_unknown_none.rs Thanks, Jamie. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel