From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: 2.6.24-rc & SB600 AHCI no go on >=4GB of RAM Date: Tue, 20 Nov 2007 10:03:01 +0900 Message-ID: <47423245.1050109@gmail.com> References: <198606.73895.qm@web52608.mail.re2.yahoo.com> <200711141317.35746.ak@suse.de> <200711141746.26793.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from rv-out-0910.google.com ([209.85.198.184]:32118 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752424AbXKTBDJ (ORCPT ); Mon, 19 Nov 2007 20:03:09 -0500 Received: by rv-out-0910.google.com with SMTP id k20so1588431rvb for ; Mon, 19 Nov 2007 17:03:08 -0800 (PST) In-Reply-To: <200711141746.26793.ak@suse.de> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Andi Kleen Cc: Thomas Gleixner , Srihari Vijayaraghavan , Ingo Molnar , linux-ide@vger.kernel.org Andi Kleen wrote: > >> The AHCI code falls back to 32bit DMA in that case. Which in turn >> causes the problem seen by Srihari. There is not much printk sticking >> necessary, the code is simply not handling this. > > What code is not handling what? > > IOMMU merging should be always safe. If it is not the driver should > not submit things in a single SG list. Yeap, a sg merged by IOMMU should be safe. It's just another contiguous memory area from the POV of the controller anyway. I wonder what went wrong here. What has exactly changed with iommu_merge patch? -- tejun