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=-11.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 D47C9C433E0 for ; Wed, 6 Jan 2021 01:29:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9619322D04 for ; Wed, 6 Jan 2021 01:29:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726394AbhAFB3r (ORCPT ); Tue, 5 Jan 2021 20:29:47 -0500 Received: from so254-31.mailgun.net ([198.61.254.31]:40719 "EHLO so254-31.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725906AbhAFB3q (ORCPT ); Tue, 5 Jan 2021 20:29:46 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1609896566; h=Content-Transfer-Encoding: MIME-Version: Message-Id: Date: Subject: Cc: To: From: Sender; bh=4p4DqJ5urwWJifyBoVvu5TpdqgDgH0bV0rmDfagihD0=; b=TQ/a51do0MsIUXOwfUgYnfD3OlbddBSc4asCVexMXpduobPG+yagguev/oeI3OslblRhw2Zp qDrsGkJk3Y7xxF4HQ5MX8Pb41MLVDobGnYZ6njBEsbZECVtPV67Ih0pMEYXwZSfzuXgJDdWQ PHYgdWGptv4NgXaIPgXTV+8lr/E= X-Mailgun-Sending-Ip: 198.61.254.31 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n10.prod.us-west-2.postgun.com with SMTP id 5ff51258d3eb3c36b4d97031 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 06 Jan 2021 01:28:56 GMT Sender: sudaraja=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id F1C8DC433ED; Wed, 6 Jan 2021 01:28:55 +0000 (UTC) Received: from th-lint-014.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: sudaraja) by smtp.codeaurora.org (Postfix) with ESMTPSA id 30F7FC433CA; Wed, 6 Jan 2021 01:28:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 30F7FC433CA Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=sudaraja@codeaurora.org From: Sudarshan Rajagopalan To: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Sudarshan Rajagopalan Subject: [PATCH 0/1] arm64: make section size configurable for memory hotplug Date: Tue, 5 Jan 2021 17:28:45 -0800 Message-Id: X-Mailer: git-send-email 2.25.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The section size defines the granularity of memory hotplug. This is currently hard coded to 1GB on arm64 linux, which defines that the least size of memblock that can be hotplugged out is 1GB. Some DDR configurations (especially low RAM and dual-rank DDRs) may have section sizes that are less than 1GB (ex. 512MB, 256MB etc.). Having an option to reduce the memblock size to section size or lower gives more granularity of memory hotplug. For example, a system with DDR section size of 512MB and kernel memblock size of 1GB, we would have to remove two segments of DDR sections in order to hotplug out atleast 1 memblock from kernel POV. Section sizes of DDRs vary based on specs (number of ranks, channels, regions etc.) Making this section size configurable helps users to assign based on the DDR being used. The default is set to 1GB which is the current memblock size. Sudarshan Rajagopalan (1): arm64: Make section size configurable for memory hotplug arch/arm64/Kconfig | 11 +++++++++++ arch/arm64/include/asm/sparsemem.h | 4 ++++ 2 files changed, 15 insertions(+) -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project