From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 29 Jun 2001 16:38:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 29 Jun 2001 16:38:42 -0400 Received: from [216.101.162.242] ([216.101.162.242]:36518 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id ; Fri, 29 Jun 2001 16:38:35 -0400 From: "David S. Miller" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15164.59159.645521.383074@pizda.ninka.net> Date: Fri, 29 Jun 2001 13:37:43 -0700 (PDT) To: Alan Cox Cc: jes@sunsite.dk (Jes Sorensen), bcrl@redhat.com (Ben LaHaise), hiren_mehta@agilent.com ("MEHTA,HIREN (A-SanJose,ex1)"), linux-kernel@vger.kernel.org ('linux-kernel@vger.kernel.org') Subject: Re: (reposting) how to get DMA'able memory within 4GB on 64-bit m achi ne In-Reply-To: In-Reply-To: <15164.18270.460245.219060@pizda.ninka.net> X-Mailer: VM 6.75 under 21.1 (patch 13) "Crater Lake" XEmacs Lucid Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Alan Cox writes: > > And when the IOMMU is "full" what happens to all the SAC only > > cards in the machine? pci_map_{single,sg}() are not allowed > > to fail. > > Thats something we already know has to be fixed. Its true with or without > an IOMMU that there may be cases where there is no free mapping space True, but my intended point is that starving the SAC-only users then returning DAC addresses to DAC-capable devices is just as unacceptable. When we have one of these compute cluster cards in the box, and Jes's suggested algorithm is used, the rest of the SAC devices in the box would be totally screwed once the IOMMU fills up. Later, David S. Miller davem@redhat.com