Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753580Ab3IXNVO (ORCPT ); Tue, 24 Sep 2013 09:21:14 -0400 Received: from mail-pb0-f50.google.com ([209.85.160.50]:55736 "EHLO mail-pb0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559Ab3IXNVM (ORCPT ); Tue, 24 Sep 2013 09:21:12 -0400 Message-ID: <52419198.1010906@gmail.com> Date: Tue, 24 Sep 2013 21:20:24 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.5) Gecko/20120607 Thunderbird/10.0.5 MIME-Version: 1.0 To: Tejun Heo CC: Zhang Yanfei , "Rafael J . Wysocki" , lenb@kernel.org, Thomas Gleixner , mingo@elte.hu, "H. Peter Anvin" , Andrew Morton , Toshi Kani , Wanpeng Li , Thomas Renninger , Yinghai Lu , Jiang Liu , Wen Congyang , Lai Jiangshan , isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, Mel Gorman , Minchan Kim , mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, Rik van Riel , jweiner@redhat.com, prarit@redhat.com, "x86@kernel.org" , linux-doc@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux MM , linux-acpi@vger.kernel.org, imtangchen@gmail.com Subject: Re: [PATCH 3/6] x86/mm: Factor out of top-down direct mapping setup References: <524162DA.30004@cn.fujitsu.com> <52416431.1090107@cn.fujitsu.com> <20130924122712.GD2366@htj.dyndns.org> In-Reply-To: <20130924122712.GD2366@htj.dyndns.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3048 Lines: 106 Hello tejun, On 09/24/2013 08:27 PM, Tejun Heo wrote: > On Tue, Sep 24, 2013 at 06:06:41PM +0800, Zhang Yanfei wrote: >> +/** >> + * memory_map_top_down - Map [map_start, map_end) top down >> + * @map_start: start address of the target memory range >> + * @map_end: end address of the target memory range >> + * >> + * This function will setup direct mapping for memory range [map_start, map_end) >> + * in a heuristic way. In the beginning, step_size is small. The more memory we >> + * map memory in the next loop. >> + */ > > The comment reads a bit weird to me. The step size is increased > gradually but that really isn't really a heuristic and it doesn't > mention mapping direction. Ok, will change the words and add the comment of direction. > > ... >> @@ -430,19 +430,13 @@ void __init init_mem_mapping(void) >> min_pfn_mapped = real_end >> PAGE_SHIFT; >> last_start = start = real_end; >> >> - /* >> - * We start from the top (end of memory) and go to the bottom. >> - * The memblock_find_in_range() gets us a block of RAM from the >> - * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages >> - * for page table. >> - */ > > I think this comment should stay here with the variable names > updated. OK, agreed > >> - while (last_start > ISA_END_ADDRESS) { >> + while (last_start > map_start) { >> if (last_start > step_size) { >> start = round_down(last_start - 1, step_size); >> - if (start < ISA_END_ADDRESS) >> - start = ISA_END_ADDRESS; >> + if (start < map_start) >> + start = map_start; >> } else >> - start = ISA_END_ADDRESS; >> + start = map_start; >> new_mapped_ram_size = init_range_memory_mapping(start, >> last_start); >> last_start = start; >> @@ -453,8 +447,32 @@ void __init init_mem_mapping(void) >> mapped_ram_size += new_mapped_ram_size; >> } >> >> - if (real_end < end) >> - init_range_memory_mapping(real_end, end); >> + if (real_end < map_end) >> + init_range_memory_mapping(real_end, map_end); >> +} >> + >> +void __init init_mem_mapping(void) >> +{ >> + unsigned long end; >> + >> + probe_page_size_mask(); >> + >> +#ifdef CONFIG_X86_64 >> + end = max_pfn << PAGE_SHIFT; >> +#else >> + end = max_low_pfn << PAGE_SHIFT; >> +#endif >> + >> + /* the ISA range is always mapped regardless of memory holes */ >> + init_memory_mapping(0, ISA_END_ADDRESS); >> + >> + /* >> + * We start from the top (end of memory) and go to the bottom. >> + * The memblock_find_in_range() gets us a block of RAM from the >> + * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages >> + * for page table. >> + */ > > And just mention the range and direction in the comment here? OK, agreed. Thanks > >> + memory_map_top_down(ISA_END_ADDRESS, end); > > Thanks. > -- Thanks. Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/