From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id DB2E66B027F for ; Mon, 28 Dec 2015 17:21:10 -0500 (EST) Received: by mail-pa0-f48.google.com with SMTP id uo6so93036955pac.1 for ; Mon, 28 Dec 2015 14:21:10 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id e65si10895581pfb.47.2015.12.28.14.21.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Dec 2015 14:21:10 -0800 (PST) Date: Mon, 28 Dec 2015 14:21:08 -0800 From: Andrew Morton Subject: Re: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Message-Id: <20151228142108.fa679ebf9d3a91ad14924977@linux-foundation.org> In-Reply-To: <1449631177-14863-1-git-send-email-izumi.taku@jp.fujitsu.com> References: <1449631109-14756-1-git-send-email-izumi.taku@jp.fujitsu.com> <1449631177-14863-1-git-send-email-izumi.taku@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Taku Izumi Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, tony.luck@intel.com, qiuxishi@huawei.com, kamezawa.hiroyu@jp.fujitsu.com, mel@csn.ul.ie, dave.hansen@intel.com, matt@codeblueprint.co.uk On Wed, 9 Dec 2015 12:19:37 +0900 Taku Izumi wrote: > This patch extends existing "kernelcore" option and > introduces kernelcore=mirror option. By specifying > "mirror" instead of specifying the amount of memory, > non-mirrored (non-reliable) region will be arranged > into ZONE_MOVABLE. > > v1 -> v2: > - Refine so that the following case also can be > handled properly: > > Node X: |MMMMMM------MMMMMM--------| > (legend) M: mirrored -: not mirrrored > > In this case, ZONE_NORMAL and ZONE_MOVABLE are > arranged like bellow: > > Node X: |MMMMMM------MMMMMM--------| > |ooooooxxxxxxooooooxxxxxxxx| ZONE_NORMAL > |ooooooxxxxxxoooooooo| ZONE_MOVABLE > (legend) o: present x: absent > > v2 -> v3: > - change the option name from kernelcore=reliable > into kernelcore=mirror > - documentation fix so that users can understand > nn[KMS] and mirror are exclusive My earlier concern with this approach is the assumption that *all* of the mirrored memory will be used to kernelcore. The user might want to use half the machine's mirrored memory for kernelcore and half for regular memory but cannot do so. However I think what I'm seeing from the discussion is that in this case, the user can alter the amount of mirrored memory via EFI to achieve the same effect. Is this correct? If so, should we document this somewhere and provide our users with instructions on how to make the required EFI changes? Or is this all so totally obvious to them that there is no need? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org