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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 044C2C05027 for ; Thu, 26 Jan 2023 16:38:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231302AbjAZQiH (ORCPT ); Thu, 26 Jan 2023 11:38:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231873AbjAZQiC (ORCPT ); Thu, 26 Jan 2023 11:38:02 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C9CB4483 for ; Thu, 26 Jan 2023 08:38:01 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F22EAB81EB4 for ; Thu, 26 Jan 2023 16:37:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7ECF3C4339C; Thu, 26 Jan 2023 16:37:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674751078; bh=YqJQPd6i+gA5E2jZwlvWvEvyUYqWpVbVfimCUEJBLMA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qOoCtEScxidUmhC1+tzaExoii3UN3nWJNV3aPzHGU/YaZyfIVd3o6XGFZi1InXRvX ZK6L960rHyONjKWliHj0QfYlIKy4KlOZZrj0G84O1FOhf875jeI2kEMQ5TXxa937YD DVtNrjQouRjYaX9XvuOssbWQ3ogaDeCIrrCrI8W0BWhDafLXT8xsomwfy48BqokVgR hDpbAFDrxtwQmjZjtgJAtBjA/+MAgJCAgKrKf7DsF3vFO/Mq4QYJmb6e1tbSUQ7LZu mJ0wAq4rY2alqAgJCcLIfn9ukYa89IHEhjtcnk6CBgzb7fMdrWwSCSpPVQloZ/roId zBZgTheNaPMbQ== Date: Thu, 26 Jan 2023 16:37:54 +0000 From: Will Deacon To: Jamie Cunliffe Cc: linux-arm-kernel@lists.infradead.org, rust-for-linux@vger.kernel.org, Miguel Ojeda , Catalin Marinas , steve.capper@arm.com Subject: Re: [PATCH 3/3] arm64: rust: Disable neon and fp target features. Message-ID: <20230126163752.GE29438@willie-the-truck> References: <20230125163739.3798252-1-Jamie.Cunliffe@arm.com> <20230125163739.3798252-4-Jamie.Cunliffe@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230125163739.3798252-4-Jamie.Cunliffe@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org On Wed, Jan 25, 2023 at 04:37:39PM +0000, Jamie Cunliffe wrote: > Disable the neon and fp target features to avoid fp & simd > registers. The use of fp-armv8 will cause a warning from rustc about > an unknown feature that is specified. The target feature is still > passed through to LLVM, this behaviour is documented as part of the > warning. This will be fixed in a future version of the rustc > toolchain. > > Signed-off-by: Jamie Cunliffe > --- > arch/arm64/Makefile | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index b53ab6aa2dfe..33ae20fc3f56 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -41,6 +41,8 @@ KBUILD_CFLAGS += -mgeneral-regs-only \ > KBUILD_CFLAGS += $(call cc-disable-warning, psabi) > KBUILD_AFLAGS += $(compat_vdso) > > +KBUILD_RUSTFLAGS += -C target-feature="-neon,-fp-armv8" Why do we advertise these features as present in scripts/generate_rust_target.rs? Will