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=-5.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 80615C4363A for ; Thu, 22 Oct 2020 08:17:51 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 0C29421481 for ; Thu, 22 Oct 2020 08:17:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="E+w6ZzfL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C29421481 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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=+/lg2rro223LfnL9SCzW2P2jxKH///B0cRl1uaWskfQ=; b=E+w6ZzfLsRGuC6UP3Lcy+fHlX YhxfRc6FVis3AvpQvYFU664qbLQwElHMKoq11oPYbtpcsR5eDKagI3HdqDQlZ9TMfwUOnf+xx6ZK7 1TSKcn/lXP6NUGAvR6oRC9004JOfUnHuJpE9PeaOe8YtHtsB++SXCyt8AcOujYQ1xeeR6vJy55CVs lAmlFAYLCM3aF32w0m+siYwFCOmHUcT8Eq0MHexiV03KaeTLEpucfQxV0JtjM5vSbiguWAl1ttKqC ao2f7HKP237zrYZC54658XRiujd2FsRmxPKHBLVEIF2Un5GSYegpZ1F8qGHBR/LKS96Y1pDtoTISm blLZjnfXw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVVlw-0000vB-Nh; Thu, 22 Oct 2020 08:16:32 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVVlt-0000uR-UY for linux-arm-kernel@lists.infradead.org; Thu, 22 Oct 2020 08:16:31 +0000 Received: from gaia (unknown [95.145.162.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 549D621481; Thu, 22 Oct 2020 08:16:27 +0000 (UTC) Date: Thu, 22 Oct 2020 09:16:24 +0100 From: Catalin Marinas To: Will Deacon Subject: Re: [RFC PATCH v2 4/4] arm64: Export id_aar64fpr0 via sysfs Message-ID: <20201022081624.GA1229@gaia> References: <20201021104611.2744565-5-qais.yousef@arm.com> <63fead90e91e08a1b173792b06995765@kernel.org> <20201021121559.GB3976@gaia> <20201021144112.GA17912@willie-the-truck> <20201021150313.ecxawwxsowweye43@e107158-lin> <20201021152310.GA18071@willie-the-truck> <20201021160730.komcgrp7q2tly55w@e107158-lin> <20201021172345.GF18071@willie-the-truck> <20201021195736.mj4njbi6pxkbpbyf@e107158-lin> <20201021202626.GA18494@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201021202626.GA18494@willie-the-truck> 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-20201022_041630_457284_2BEBE6D5 X-CRM114-Status: GOOD ( 28.81 ) 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, "Peter Zijlstra \(Intel\)" , Marc Zyngier , Morten Rasmussen , James Morse , Greg Kroah-Hartman , Linus Torvalds , Qais Yousef , 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 21, 2020 at 09:26:27PM +0100, Will Deacon wrote: > On Wed, Oct 21, 2020 at 08:57:36PM +0100, Qais Yousef wrote: > > On 10/21/20 18:23, Will Deacon wrote: > > > On Wed, Oct 21, 2020 at 05:07:30PM +0100, Qais Yousef wrote: > > > > > > For example, the new sysctl_enable_asym_32bit could be a cpumask instead of > > > > > > a bool as it currently is. Or we can make it a cmdline parameter too. > > > > > > In both cases some admin (bootloader or init process) has to ensure to fill it > > > > > > correctly for the target platform. The bootloader should be able to read the > > > > > > registers to figure out the mask. So more weight to make it a cmdline param. > > > > > > > > > > I think this is adding complexity for the sake of it. I'm much more in > > > > > > > > I actually think it reduces complexity. No special ABI to generate the mask > > > > from the kernel. The same opt-in flag is the cpumask too. > > > > > > Maybe I'm misunderstanding your proposal but having a cpumask instead of > > > > What I meant is that if we change the requirement to opt-in from a boolean > > switch > > > > sysctl.enable_32bit_asym=1 > > > > to require the bootloader/init scripts provide the mask of aarch32 capable cpus > > > > sysctl.asym_32bit_cpus=0xf0 [...] > > * We don't need a separate API to export which cpus are 32bit capable. > > They can read it directly from /proc/sys/kernel/asym_32bit_cpus. > > When it's 0 it means the system is not asymmetric. > > I don't see how this is better than a separate cpumask for this purpose. > It feels like you're trying to overload the control and the identification, > but that just makes things confusing and hard to use as I now need to know > which logical CPUs correspond to which physical CPUs in order to set the > command-line. I agree. Let's leave the identification to the kernel as it has access to the CPUID registers and can provide the cpumask. The control in this case doesn't need to be more than a boolean and its meaning is that the user knows what it is doing. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel