Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750709AbVILKDU (ORCPT ); Mon, 12 Sep 2005 06:03:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750711AbVILKDU (ORCPT ); Mon, 12 Sep 2005 06:03:20 -0400 Received: from clock-tower.bc.nu ([81.2.110.250]:42448 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1750709AbVILKDT (ORCPT ); Mon, 12 Sep 2005 06:03:19 -0400 Subject: Re: [1/3] Add 4GB DMA32 zone From: Alan Cox To: Andi Kleen Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org, discuss@x86-64.org In-Reply-To: <43246267.mailL4R11PXCB@suse.de> References: <43246267.mailL4R11PXCB@suse.de> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 12 Sep 2005 11:28:19 +0100 Message-Id: <1126520900.30449.48.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 915 Lines: 22 > One argument was still if the zone should be 4GB or 2GB. The main > motivation for 2GB would be an unnamed not so unpopular hardware > raid controller (mostly found in older machines from a particular four letter > company) who has a strange 2GB restriction in firmware. But Adaptec AACRAID is one offender > that one works ok with swiotlb/IOMMU anyways, so it doesn't really Old aacraid actually cannot use IOMMU. It isn't alone in that limitation. Most hardware that has a 30/31bit limit can't go via the IOMMU because IOMMU space appears on the bus above 2GB so is itself invisible to the hardware. Other devices with similar limits include the broadcomm b44 - 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/