From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [PATCH] [29/82] x86_64: Rename IOMMU option, fix help and mark option embedded. Date: Sat, 24 Jun 2006 19:14:33 -0400 Message-ID: <20060624231433.GA24862@devserv.devel.redhat.com> References: <449C852C.mailCZT11F9YB@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx1.redhat.com ([66.187.233.31]:60082 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751165AbWFXXOm (ORCPT ); Sat, 24 Jun 2006 19:14:42 -0400 Content-Disposition: inline In-Reply-To: <449C852C.mailCZT11F9YB@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andi Kleen Cc: torvalds@osdl.org, discuss@x86-64.org, akpm@osdl.org, markh@osdl.org, alan@redhat.com, linux-scsi@vger.kernel.org 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 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. Yeah its ugly, but its old hw and its a one off that can do without tangling the core code. At least thats what you decided last time around ;)