From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CAE251B4F0A for ; Thu, 24 Jul 2025 17:46:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753379185; cv=none; b=egt7JSm4xGrVv1tHQhgiV1xMKqaldKdrpEG9b3hHI6G6msrVzvu2kbiO0hxvmrZAQvl9nMpIY24BCsW8uP45GG48OhxvWFbu+CQg0x3VOLGw+kr1toeQGBlUIVSiEi8x4+gSGXvNCm77n79ECwg0ueiy8XZ/xgfBrQ2Lrvc6j2s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753379185; c=relaxed/simple; bh=i/Kpz+Ste+Djqg4BpNd41PAeFUiI434DZcyDd+zWh+A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mP+rKGQVByyMkncs9tLlEs+SUjCW848YVTJ5tzz5SdLGd82gxoRu1X8yZDFa7r4/on4NqO75iD1ZjJNDaTFgc3QWZLQLD1CVY2XpGRqOaAxBFiLhSyLSkH/6zxdGPEL7zUdK0bJjoK1vsBCJg5cKvFMycRD5QvI990FJTqvOZ/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=kSRcuRqp; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="kSRcuRqp" 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=ZCg+1QoRbgtlHKqHHRGHpdwt2kaPrsylpaRAX7tlZ98=; b=kSRcuRqp2hSV2mCRQ5JKkdZmnI rChDz5dy7d9lgGVJ8iIjVuUvhVEi6Fj+1IhO1mNpVSnTSKrVDMuJBo5TxayvowmGemNxdNuWfx0GV 3Cgf65hQMP8zGV5ajpGa6GN/K9sJS1XqkQyEQQfPTOw8g09CWvnc+duS64f33U8AklDHI1SlKXz4H 4UOybKFir40fJsuqS68elFYqRNl5t4UDm0RRr2LMvzFwWtS0qtl2Xqtw2W6u08WH2SncRLmJ/Gz3e rVwf2vEn32V13KSb2CqvK5TAbTuZ1zW89R/mg9y2a/XCNj/65vE/jNeMXkGlpOj3Gozm+wfbJgCo6 vP4mgNRg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:40504) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uf014-0003co-15; Thu, 24 Jul 2025 18:46:02 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.96) (envelope-from ) id 1uf00z-0000v7-0L; Thu, 24 Jul 2025 18:45:57 +0100 Date: Thu, 24 Jul 2025 18:45:56 +0100 From: "Russell King (Oracle)" To: Suchit Karunakaran Cc: ardb@kernel.org, linus.walleij@linaro.org, ebiggers@google.com, nathan@kernel.org, lumag@kernel.org, dave@vasilevsky.ca, ruanjinjie@huawei.com, kees@kernel.org, liuyuntao12@huawei.com, linux-arm-kernel@lists.infradead.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm: allow single CPU configuration by adjusting NR_CPUS range and defaults Message-ID: References: <20250724172603.18701-1-suchitkarunakaran@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250724172603.18701-1-suchitkarunakaran@gmail.com> Sender: Russell King (Oracle) On Thu, Jul 24, 2025 at 10:56:03PM +0530, Suchit Karunakaran wrote: > Previously, the NR_CPUS config for ARM required a minimum of 2 CPUs. > This patch changes the minimum NR_CPUS to 1 when SMP is not enabled, > sets range to exactly 1 if !SMP, allowing only a single CPU setting and > adds conditional defaults: > - default to 1 if SMP is disabled (uniprocessor) > - default to 4 if SMP is enabled (multiprocessor) > > Signed-off-by: Suchit Karunakaran This hasn't been tested. NR_CPUS depends on SMP, so if SMP is not enabled, then NR_CPUS doesn't exist in the configuration. Therefore, providing a default for !SMP is meaningless. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!