Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752140AbWCCB7X (ORCPT ); Thu, 2 Mar 2006 20:59:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752141AbWCCB7W (ORCPT ); Thu, 2 Mar 2006 20:59:22 -0500 Received: from fmr21.intel.com ([143.183.121.13]:46309 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S1752140AbWCCB7W convert rfc822-to-8bit (ORCPT ); Thu, 2 Mar 2006 20:59:22 -0500 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [Patch] Move swiotlb_init early on X86_64 Date: Thu, 2 Mar 2006 17:59:10 -0800 Message-ID: <88056F38E9E48644A0F562A38C64FB60076C30F4@scsmsx403.amr.corp.intel.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [Patch] Move swiotlb_init early on X86_64 Thread-Index: AcY+YtYT2hXESft7TBWbnHtnkLJolAAApQiQ From: "Pallipadi, Venkatesh" To: "Andi Kleen" , "Zou, Nanhai" Cc: "Zhang, Yanmin" , "Luck, Tony" , "LKML" , "Andrew Morton" X-OriginalArrivalTime: 03 Mar 2006 01:59:11.0748 (UTC) FILETIME=[10E22440:01C63E66] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1503 Lines: 42 >-----Original Message----- >From: Andi Kleen [mailto:ak@suse.de] >Sent: Thursday, March 02, 2006 5:32 PM >To: Zou, Nanhai >Cc: Zhang, Yanmin; Luck, Tony; LKML; Andrew Morton; Pallipadi, >Venkatesh >Subject: Re: [Patch] Move swiotlb_init early on X86_64 > >On Friday 03 March 2006 00:35, Zou Nan hai wrote: > >> This patch modify the bootmem allocator, >> let normal bootmem allocation on 64 bit system first go above 4G >> address. > >That's very ugly and likely to break some architectures. Sorry >but #ifdefs is the wrong way to do this. > >Passing a limit parameter is better and use that in the swiotlb >allocation. If you're worried about changing too many callers >you could add a new entry point. > Another potential issue with this approach: On a 64 bit system with less than 4G phys memory, we will fail to get any memory above 4G and fall back to start from '0'. This is different from original behaviour, where goal was MAX_DMA_ADDRESS (16M) and we would allocate memory starting from 16M. As a result, we will now eat up memory in 0-16M range and may break some legacy drivers as they will not get any memory. If we go this way, then we should fallback to original goal if we are not able to get greater than 4G memory. Thanks, Venki - 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/