Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752036Ab0DDHbI (ORCPT ); Sun, 4 Apr 2010 03:31:08 -0400 Received: from smtp-out002.kontent.com ([81.88.40.216]:32980 "EHLO smtp-out002.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751553Ab0DDHa6 convert rfc822-to-8bit (ORCPT ); Sun, 4 Apr 2010 03:30:58 -0400 From: Oliver Neukum To: "tek-life" Subject: Re: Can we remove the Zone_DMA? Date: Sun, 4 Apr 2010 09:31:00 +0200 User-Agent: KMail/1.12.4 (Linux/2.6.34-rc2-0.1-default; KDE/4.3.5; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, ebiederm@xmission.com References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="gb2312" Content-Transfer-Encoding: 8BIT Message-Id: <201004040931.00634.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 849 Lines: 18 Am Sonntag, 4. April 2010 06:21:54 schrieb tek-life: > 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. Floppy disks & paralell ports still use DMA Regards Oliver -- 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/