From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751475AbaANMVs (ORCPT ); Tue, 14 Jan 2014 07:21:48 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:60355 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999AbaANMVp (ORCPT ); Tue, 14 Jan 2014 07:21:45 -0500 Message-ID: <52D538FD.8010907@ti.com> Date: Tue, 14 Jan 2014 15:17:49 +0200 From: Grygorii Strashko User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Philipp Hachtmann , , CC: , , , , , , , , 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> In-Reply-To: <1389618217-48166-3-git-send-email-phacht@linux.vnet.ibm.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.145.75] X-EXCLAIMER-MD-CONFIG: f9c360f5-3d1e-4c3c-8703-f45bf52eff6b Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Seems, it would be safer to track separately memory, available for Linux ("memory" regions), and real phys memory. For example: - add memblock type "phys_memory" and update it each time memblock_add()/memblock_remove() are called, but don't update, if memblock_nomap()/memblock_remap() are called? Another question is - Should the real phys memory configuration data be a part of memblock or not? Also, I like more memblock_steal()/memblock_reclaim() names for new APIs ) regards, -grygorii