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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 74A6BC433DF for ; Tue, 19 May 2020 16:14:48 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 41DFF2075F for ; Tue, 19 May 2020 16:14:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tAVjw9w5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41DFF2075F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0EjJg5Z9DqLY2MxPjNeYR5Xa9ZCiqnKAOWk3VesCh5c=; b=tAVjw9w5bHLnvJ sVoWdNpF9mQUXzJja8b9yYKL93zJDbTSi6P3LLZ4m9WGvJZz4ATiKNNaSn/rl0uJSdilJONFWDT73 VNtlx7yqq+74B4LR0Qd8VOoCkUHDnHlZHBLPqc0tQGmk3/cIV8Yyt4vrxrUx9N5bsm596Mcw7G747 1bIT9kaj1mGLfBB86o5iUUVJjB+wp9gYUQOuDzUv7xluYReKV8kTixuehJGM3aCSbpbMZTBvI7ryb foLUn1Z38/t6k0tOumq2X7G59kah2VeYNTa2O6VBVXurMxJxh4uBlR3ieroATx4tfWUKmbDxNR8BP UjQZYcXEw69Rmyu4z6sg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jb4tD-0007r0-Nh; Tue, 19 May 2020 16:14:47 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jb4t9-0007q6-Ft for linux-arm-kernel@lists.infradead.org; Tue, 19 May 2020 16:14:45 +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 60B3730E; Tue, 19 May 2020 09:14:42 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D46BB3F305; Tue, 19 May 2020 09:14:40 -0700 (PDT) Date: Tue, 19 May 2020 17:14:34 +0100 From: Catalin Marinas To: Vladimir Murzin Subject: Re: [PATCH v4 24/26] arm64: mte: Introduce early param to disable MTE support Message-ID: <20200519161434.GF20313@gaia> References: <20200515171612.1020-1-catalin.marinas@arm.com> <20200515171612.1020-25-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200519_091444_334177_C8183D36 X-CRM114-Status: GOOD ( 18.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Will Deacon , Szabolcs Nagy , Andrey Konovalov , Kevin Brodsky , linux-mm@kvack.org, Vincenzo Frascino , Peter Collingbourne , Dave P Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 18, 2020 at 12:26:30PM +0100, Vladimir Murzin wrote: > On 5/15/20 6:16 PM, Catalin Marinas wrote: > > For performance analysis it may be desirable to disable MTE altogether > > via an early param. Introduce arm64.mte_disable and, if true, filter out > > the sanitised ID_AA64PFR1_EL1.MTE field to avoid exposing the HWCAP to > > user. > > > > Signed-off-by: Catalin Marinas > > Cc: Will Deacon > > --- > > > > Notes: > > New in v4. > > > > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > > arch/arm64/kernel/cpufeature.c | 11 +++++++++++ > > 2 files changed, 15 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index f2a93c8679e8..7436e7462b85 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -373,6 +373,10 @@ > > arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards > > Format: ,, > > > > + arm64.mte_disable= > > + [ARM64] Disable Linux support for the Memory > > + Tagging Extension (both user and in-kernel). > > + > > Should it really to take parameter (on/off/true/false)? It may lead to expectation > that arm64.mte_disable=false should enable MT and, yes, double negatives make it > look ugly, so if we do need parameter, can it be arm64.mte=on/off/true/false? My reasoning about arm64.mte= was that 'on' may lead people to think it does something even when MTE isn't available on the SoC. So I ended up with an explicit 'disable' in the name. Happy to change it if we don't drop this parameter altogether (in the absence of valid use-cases). -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel