From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932766AbcHKKIK (ORCPT ); Thu, 11 Aug 2016 06:08:10 -0400 Received: from foss.arm.com ([217.140.101.70]:53125 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752449AbcHKKIF (ORCPT ); Thu, 11 Aug 2016 06:08:05 -0400 Date: Thu, 11 Aug 2016 11:07:32 +0100 From: Catalin Marinas To: Xishi Qiu Cc: Will Deacon , Linux MM , LKML , chenjie6@huawei.com Subject: Re: arm64: why set SECTION_SIZE_BITS to 1G size? Message-ID: <20160811100732.GA18366@e104818-lin.cambridge.arm.com> References: <57AC490E.4080204@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57AC490E.4080204@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 11, 2016 at 05:44:46PM +0800, Xishi Qiu wrote: > arm64: > SECTION_SIZE_BITS 30 -----1G > > The memory hotplug(add_memory -->check_hotplug_memory_range) > must be aligned with section.So I can not add mem with 64M ... > Can I modify the SECTION_SIZE_BITS to 26? There was a patch to reduce this to 27: http://lkml.kernel.org/g/1465821119-3384-1-git-send-email-jszhang@marvell.com Also some discussions in this thread on a different patch: http://lkml.iu.edu/hypermail/linux/kernel/1604.1/03036.html Does your system really have such small alignment memory blocks? -- Catalin