Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756499Ab1DRTGY (ORCPT ); Mon, 18 Apr 2011 15:06:24 -0400 Received: from 8bytes.org ([88.198.83.132]:50004 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756455Ab1DRTGV (ORCPT ); Mon, 18 Apr 2011 15:06:21 -0400 Date: Mon, 18 Apr 2011 21:06:20 +0200 From: Joerg Roedel To: "H. Peter Anvin" Cc: "Roedel, Joerg" , Ingo Molnar , Thomas Gleixner , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Yinghai Lu Subject: Re: [PATCH 1/4] x86, gart: Don't enforce GART aperture lower-bound by alignment Message-ID: <20110418190620.GD8155@8bytes.org> References: <1303134346-5805-1-git-send-email-joerg.roedel@amd.com> <1303134346-5805-2-git-send-email-joerg.roedel@amd.com> <4DAC4E7F.1010502@zytor.com> <20110418145653.GI2192@amd.com> <4DAC5E16.1020408@zytor.com> <20110418173655.GA8155@8bytes.org> <4DAC7739.2060100@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DAC7739.2060100@zytor.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1144 Lines: 23 On Mon, Apr 18, 2011 at 10:39:05AM -0700, H. Peter Anvin wrote: > I'm going to apply your patch as-is, based on the notion that this is a > change of mechanism, and a change of policy is a separate thing. > However, we should address the shutdown of the GART first, and then we > can move the start address to zero (again, two separate patches.) Hmm, thinking again about this, setting the lower-bound to 0 may break kdump setups. The kdump kernel is then able to allocate an aperture too and that may use half of the memory from the kdump-system so that the dump-process triggers OOM. As it is now, the GART is automatically disabled when the BIOS doesn't setup it correctly and the machine has not more than 512MB of memory. Either we keep it as is or, with the changes suggested above, we handle it like soft-iotlb and don't use gart for dma-api at all when max_pfn is smaller than 4G. Joerg -- 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/