From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Travis Subject: Re: [PATCH]: x86_64, audio: Fix system panic when DMA > 40 bits Date: Thu, 02 May 2013 11:59:28 -0700 Message-ID: <5182B790.6090907@sgi.com> References: <1367435048-66137-1-git-send-email-travis@sgi.com> <518205A9.1050409@canonical.com> <5182AE68.9010905@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5182AE68.9010905@wwwdotorg.org> Sender: linux-kernel-owner@vger.kernel.org To: Stephen Warren Cc: David Henningsson , Stephen Warren , Jaroslav Kysela , Takashi Iwai , Pierre-Louis Bossart , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Russ Anderson List-Id: alsa-devel@alsa-project.org On 5/2/2013 11:20 AM, Stephen Warren wrote: > On 05/02/2013 12:20 AM, David Henningsson wrote: >> On 05/01/2013 09:04 PM, Mike Travis wrote: >>> The audio driver mistakenly allows 64 bit addresses to be created for >>> the audio driver on Nvidia GPUs. Unfortunately, the hardware normally >>> only supports up to 40 bits of DMA. This can cause system panics as >>> well as misdirected data when the address is > 40 bits as the upper >>> part the address is truncated. >> >> Thanks for this patch. Stephen Warren, is this something you can >> confirm/deny, and do you know what range of hardware this actually >> applies to? > > It's certainly plausible that the GPU's internal physical addresses are > less than a full 64-bits, and this probably affects PCI accesses too. > I haven't noticed any other problems with MMIOH accesses. The problem of DMA32 addresses certainly affects us though audio is not a high priority on UV(*) except in specific applications (like Media Servers, etc.] Accesses to the GPU and GPGPU are much more common. (* http://www.sgi.com/products/servers/uv/)