From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH] [29/82] x86_64: Rename IOMMU option, fix help and mark option embedded. Date: Sun, 25 Jun 2006 17:22:23 +0200 Message-ID: <200606251722.23294.ak@suse.de> References: <449C852C.mailCZT11F9YB@suse.de> <20060624231433.GA24862@devserv.devel.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from ns2.suse.de ([195.135.220.15]:51344 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1751432AbWFYPWf (ORCPT ); Sun, 25 Jun 2006 11:22:35 -0400 In-Reply-To: <20060624231433.GA24862@devserv.devel.redhat.com> Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Alan Cox Cc: torvalds@osdl.org, discuss@x86-64.org, akpm@osdl.org, markh@osdl.org, linux-scsi@vger.kernel.org, axboe@suse.de On Sunday 25 June 2006 01:14, Alan Cox wrote: > On Sat, Jun 24, 2006 at 02:19:56AM +0200, Andi Kleen wrote: > > To my astonishment I discovered the aacraid driver tests this > > symbol directly. This looks quite broken to me - it's an internal > > implementation detail of the PCI DMA API. Can the maintainer > > please clarify what this test was intended to do? > > Shouldn't be to your astonishment, you were involved in the process Can't remember sorry. > Older aacraid hardware cannot address the 3-4GB range where the iommu > remaps pages. As the PCI DMA implementation for the x86-64 is flawed and > doesn't support any nice way to deal with this via swiotlb instead the > driver handles it internally. Then you should just force a low bounce pfn < 0xfffffff for the block device - then the block layer should use GFP_DMA bouncing. -Andi