Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752362Ab0DGCTk (ORCPT ); Tue, 6 Apr 2010 22:19:40 -0400 Received: from terminus.zytor.com ([198.137.202.10]:48215 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153Ab0DGCTf (ORCPT ); Tue, 6 Apr 2010 22:19:35 -0400 Message-ID: <4BBBE976.1000603@zytor.com> Date: Tue, 06 Apr 2010 19:09:58 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Venkatram Tummala CC: Xianghua Xiao , Youngwhan Song , Joel Fernandes , Frank Hu , hayfeng Lee , "linux-kernel@vger.kernel.org" , "linux-kernel@zh-kernel.org" , "kernelnewbies@nl.linux.org" Subject: Re: why choose 896MB to the start point of ZONE_HIGHMEM References: <4BBB7AC9.5060008@zytor.com> <4BBB8F07.60401@zytor.com> <3715922601579231267@unknownmsgid> <4BBBC470.4050002@zytor.com> In-Reply-To: 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: 914 Lines: 29 On 04/06/2010 07:04 PM, Venkatram Tummala wrote: > Hey Xiao, > > last 128MB is not used for highmem. last 128MB is used for data > structures(page tables etc.) to support highmem . Highmem is not > something which is "INSIDE" Kernel's Virtual Address space. Highmem > refers to a region of "Physical memory" which can be mapped into > kernel's virtual address space through page tables. > > Regards, > Venkatram Tummala > Not quite. The vmalloc region is for *anything which is dynamically mapped*, which includes I/O, vmalloc, and HIGHMEM (kmap). -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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/