From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: What's the SB600 64-bit DMA problem? Date: Mon, 29 Sep 2008 08:20:12 +0900 Message-ID: <48E0112C.7010901@gmail.com> References: <20080920151712.10515.qmail@science.horizon.com> <20080921001529.23400.qmail@science.horizon.com> <65a6ef750809231730h52f6bf47g23b33db1d2f4ca08@mail.gmail.com> <48DA0C8B.3000406@gmail.com> <20080925032437.6802.qmail@science.horizon.com> <48DCEC6D.1040305@gmail.com> <20080928210422.2578.qmail@science.horizon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ti-out-0910.google.com ([209.85.142.184]:33195 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752923AbYI1XVj (ORCPT ); Sun, 28 Sep 2008 19:21:39 -0400 Received: by ti-out-0910.google.com with SMTP id b6so784938tic.23 for ; Sun, 28 Sep 2008 16:21:36 -0700 (PDT) In-Reply-To: <20080928210422.2578.qmail@science.horizon.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: George Spelvin Cc: Shane.Huang@amd.com, mdnelson8@gmail.com, linux-ide@vger.kernel.org, jgarzik@redhat.com, grundler@google.com George Spelvin wrote: > Tejun Heo wrote: >>> Q: Does the fact that I'm using the GART IOMMU mean that I'm not really using >>> using 64-bit DMA at all? >> Can you turn it off and see what happens? > > I can if I can verify that every other bus-master PCI device in the > system can do 64-bit DMA. > > Do you know how to check that? I haven't found a file under /sys or > /proc that tells me what the DMA masks are of various system > drivers, but that doesn't mean that it doesn't exist. It doesn't really matter. The kernel will bounce buffers as necessary. -- tejun