From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f46.google.com (mail-wm0-f46.google.com [74.125.82.46]) by kanga.kvack.org (Postfix) with ESMTP id 82C396B027C for ; Mon, 7 Dec 2015 19:31:15 -0500 (EST) Received: by wmuu63 with SMTP id u63so161930726wmu.0 for ; Mon, 07 Dec 2015 16:31:15 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id o16si26916566wmd.116.2015.12.07.16.31.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Dec 2015 16:31:14 -0800 (PST) Date: Mon, 7 Dec 2015 16:31:12 -0800 From: Andrew Morton Subject: Re: [PATCH v2 0/2] mm: Introduce kernelcore=reliable option Message-Id: <20151207163112.930a495d24ab259cad9020ac@linux-foundation.org> In-Reply-To: <1448636635-15946-1-git-send-email-izumi.taku@jp.fujitsu.com> References: <1448636635-15946-1-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 Sat, 28 Nov 2015 00:03:55 +0900 Taku Izumi wrote: > Xeon E7 v3 based systems supports Address Range Mirroring > and UEFI BIOS complied with UEFI spec 2.5 can notify which > ranges are reliable (mirrored) via EFI memory map. > Now Linux kernel utilize its information and allocates > boot time memory from reliable region. > > My requirement is: > - allocate kernel memory from reliable region > - allocate user memory from non-reliable region > > In order to meet my requirement, ZONE_MOVABLE is useful. > By arranging non-reliable range into ZONE_MOVABLE, > reliable memory is only used for kernel allocations. > > My idea is to extend existing "kernelcore" option and > introduces kernelcore=reliable option. By specifying > "reliable" instead of specifying the amount of memory, > non-reliable region will be arranged into ZONE_MOVABLE. It is unfortunate that the kernel presently refers to this memory as "mirrored", but this patchset introduces the new term "reliable". I think it would be better if we use "mirrored" throughout. Of course, mirroring isn't the only way to get reliable memory. Perhaps if a part of the system memory has ECC correction then this also can be accessed using "reliable", in which case your proposed naming makes sense. reliable == mirrored || ecc? Secondly, does this patchset mean that kernelcore=reliable and kernelcore=100M are exclusive? Or can the user specify "kernelcore=reliable,kernelcore=100M" to use 100M of reliable memory for kernelcore? This is unclear from the documentation and I suggest that this be spelled out. -- 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