From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yh0-f48.google.com (mail-yh0-f48.google.com [209.85.213.48]) by kanga.kvack.org (Postfix) with ESMTP id 9BE636B0036 for ; Tue, 14 Jan 2014 09:30:11 -0500 (EST) Received: by mail-yh0-f48.google.com with SMTP id f11so109482yha.35 for ; Tue, 14 Jan 2014 06:30:11 -0800 (PST) Received: from arroyo.ext.ti.com (arroyo.ext.ti.com. [192.94.94.40]) by mx.google.com with ESMTPS id j24si1072101yhb.71.2014.01.14.06.30.10 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 14 Jan 2014 06:30:10 -0800 (PST) Message-ID: <52D548B1.8000504@ti.com> Date: Tue, 14 Jan 2014 09:24:49 -0500 From: Santosh Shilimkar MIME-Version: 1.0 Subject: Re: [PATCH V3 2/2] mm/memblock: Add support for excluded memory areas References: <1389618217-48166-1-git-send-email-phacht@linux.vnet.ibm.com> <1389618217-48166-3-git-send-email-phacht@linux.vnet.ibm.com> <52D538FD.8010907@ti.com> In-Reply-To: <52D538FD.8010907@ti.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Philipp Hachtmann Cc: Grygorii Strashko , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qiuxishi@huawei.com, dhowells@redhat.com, daeseok.youn@gmail.com, liuj97@gmail.com, yinghai@kernel.org, zhangyanfei@cn.fujitsu.com, tangchen@cn.fujitsu.com On Tuesday 14 January 2014 08:17 AM, Grygorii Strashko wrote: > Hi Philipp, > > On 01/13/2014 03:03 PM, Philipp Hachtmann wrote: >> Add a new memory state "nomap" to memblock. This can be used to truncate >> the usable memory in the system without forgetting about what is really >> installed. > > > Sorry, but this solution looks a bit complex (and probably wrong - from design point of view)) > if you need just to fix memblock_start_of_DRAM()/memblock_end_of_DRAM() APIs. > > More over, other arches use at least below APIs: > - memblock_is_region_memory() !!! > - for_each_memblock(memory, reg) !!! > - __next_mem_pfn_range() !!! > - memblock_phys_mem_size() > - memblock_mem_size() > - memblock_start_of_DRAM() > - memblock_end_of_DRAM() > with assumption that "memory" regions array have been updated > when mem block is stolen (no-mapped), as result this change may > have unpredictable side effects :( if these new APIs > will be re-used (for ARM arch, as example). > > You can take a look on how ARM is using arm_memblock_steal() - > the stolen memory is not accounted any more. > I was also wondering instead of nomap state, the memblock_add/remove() will do the same trick. arm_memblock_steal() wrapper does achieve similar functionality of reserving the DRAM without mapping it into the Linux. Why not just use the same idea ? Regards, Santosh -- 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