From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756184AbZEHHpv (ORCPT ); Fri, 8 May 2009 03:45:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757380AbZEHHpm (ORCPT ); Fri, 8 May 2009 03:45:42 -0400 Received: from vpn.id2.novell.com ([195.33.99.129]:49618 "EHLO vpn.id2.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755302AbZEHHpl convert rfc822-to-8bit (ORCPT ); Fri, 8 May 2009 03:45:41 -0400 Message-Id: <4A03FF94.76EA.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 8.0.0 Date: Fri, 08 May 2009 08:47:00 +0100 From: "Jan Beulich" To: "Jeremy Fitzhardinge" Cc: "Jeremy Fitzhardinge" , "Ingo Molnar" , "the arch/x86 maintainers" , "FUJITA Tomonori" , "Xen-devel" , "Linux Kernel Mailing List" Subject: Re: [Xen-devel] [PATCH 1/9] xen: make sure swiotlb allocation isphysically contigious References: <1241741842-7966-1-git-send-email-jeremy@goop.org> <1241741842-7966-2-git-send-email-jeremy@goop.org> In-Reply-To: <1241741842-7966-2-git-send-email-jeremy@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> Jeremy Fitzhardinge 08.05.09 02:17 >>> >Impact: make swiotlb allocation suitable for Xen > >When allocating the swiotlb buffer under Xen, make sure the memory is >physically contiguous so that its really suitable for DMA. > >Do this by allocating the memory as usual, but then call a Xen >function to rearrange the underlying pages to be physically >contiguous. As pointed out before, you must not use alloc_bootmem_low...() here, as on large systems you may otherwise get an allocation failure (i.e. a panic - checking the return value is pointless). The alternative is to fix the bootmem allocator to no longer allocate from bottom up. Jan