Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752517Ab0DDIia (ORCPT ); Sun, 4 Apr 2010 04:38:30 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:34824 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752184Ab0DDIiX (ORCPT ); Sun, 4 Apr 2010 04:38:23 -0400 To: tek-life Cc: dhazelton@enter.net, oliver@neukum.org, linux-kernel@vger.kernel.org Subject: Re: Can we remove the Zone_DMA? References: <201004040349.28840.dhazelton@enter.net> From: ebiederm@xmission.com (Eric W. Biederman) Date: Sun, 04 Apr 2010 01:38:17 -0700 In-Reply-To: (tek-life's message of "Sun\, 4 Apr 2010 16\:28\:49 +0800") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: teklife.kernel@gmail.com, linux-kernel@vger.kernel.org, oliver@neukum.org, dhazelton@enter.net X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in01.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1186 Lines: 27 tek-life writes: > Thanks for your replys. > I was confused. The motherboard of Intel i810 chipset in early 1999 > had not supported the ISA. You say keyboard should use ISA, what > should work for the pc using the i810 motherboard. More important , > the keyboard don't use DMA. Last I heard this discussed it was mentioned that there were some fairly common integrated sound devices using ISA DMA. As for the i810 chipset not supporting ISA that isn't really true. No one implements ISA plug-in slots, but at least in the for of LPC hardware that is effectively ISA continues to be supported for various legacy devices. Ultimately I don't see much point in disabling ZONE_DMA. It is a lot of work to track down if it is really needed, and it only costs 16MB. So unless someone shows me that ZONE_DMA triggers the OOM killer unnecessarily or otherwise impacts the system what does legacy code hurt? Eric -- 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/