Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751292Ab0DDFdR (ORCPT ); Sun, 4 Apr 2010 01:33:17 -0400 Received: from mail-iw0-f197.google.com ([209.85.223.197]:52837 "EHLO mail-iw0-f197.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843Ab0DDFdL convert rfc822-to-8bit (ORCPT ); Sun, 4 Apr 2010 01:33:11 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=fNfln1nviekD13NbBZzqUvEyIx878b3ztfZ6G1ii8l+QtNQSUdWgAYx3/gExo4qNLk ZUfGaBIM1QnLyY7Dh4dSZVypHwrzWclxvFtO2mAwTB31Z7JLmaT1UuT9QsOiJJpY/aEa Btso9WwaROVEPQYVGM7Ssl+GxkSjJRPZH4Yx8= MIME-Version: 1.0 In-Reply-To: References: <201004040107.15783.dhazelton@enter.net> Date: Sun, 4 Apr 2010 13:33:09 +0800 X-Google-Sender-Auth: 2508f8d0b896fc19 Message-ID: Subject: Fwd: Can we remove the Zone_DMA? From: tek-life To: dhazelton@enter.net Cc: linux-kernel@vger.kernel.org, ebiederm@xmission.com Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2242 Lines: 60 Thanks for your reply.And do you means that , If I use a modern PC,such as my pc (CPU:Intel dual-core 2.6GHZ; Memory 2GB; And no pci ).I can remove the ZONE_DMA .And make sure this system also run smoothly as before? ?? 2010??4??4?? ????1:07??Daniel Hazelton ะด???? On Sunday 04 April 2010 12:21:54 am tek-life wrote: > > I??m a newbie on the linux kernel. Now I am reading the source code of > > Linux . I have a question in the following about ZONE_DMA. > > > > > > In Linux , The Memory is divided to three zone. They are ZONE_DMA > > ??ZONE_NORMAL and ZONE_HIGHMEM. From the book of "Undstand the Linux > > kernel ", the ZONE_DMA has the effect that the Direct Memory Access > > (DMA) processors for old ISA buses have a strong limitation: they are > > able to address only the first 16 MB of RAM. SO ,we must set a zone > > for the DMA on ISA bus. And I suspect that the hardware has > > developed so quickly .And in this days the ISA has been weeded out. > > And so ,if we not defined the ZONE_DMA, is the system be effected? And > > why not remove ZONE_DMA from the kernel . If it cann??t to do so??the > > compatibility is the only reason? > > While ISA is gone as a true peripheral interconnect for new systems it > does, > actually, still live on in a lot of systems that Linux still supports. > While > those systems, generally, are running the same kernel and userspace they > were > a decade ago I have no doubt that somebody might find an old machine and > put > Linux on it - just because they could. > > And that also discounts the non-IBM PC machines that are out there that > Linux > also supports. While I don't know enough about them to say for sure, I am > quite certain that at least some of them are still using the ISA bus. > > DRH > -- Laboratory of Service Computing Technology and System p-web:http://tek-life.org/blog QQ:150439216 -- Laboratory of Service Computing Technology and System p-web:http://tek-life.org/blog QQ:150439216 -- 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/