From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756704AbZFBOiW (ORCPT ); Tue, 2 Jun 2009 10:38:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754955AbZFBOhL (ORCPT ); Tue, 2 Jun 2009 10:37:11 -0400 Received: from va3ehsobe004.messaging.microsoft.com ([216.32.180.14]:15776 "EHLO VA3EHSOBE004.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755174AbZFBOhJ (ORCPT ); Tue, 2 Jun 2009 10:37:09 -0400 X-SpamScore: 4 X-BigFish: VPS4(ze80izzz1202hzzz32i17ch43j) X-FB-SS: 5, X-WSS-ID: 0KKM8LD-04-0I3-01 From: Joerg Roedel To: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org CC: akpm@linux-foundation.org, Joerg Roedel Subject: [PATCH 4/4] dma-debug: add documentation for the driver filter Date: Tue, 2 Jun 2009 16:36:44 +0200 Message-ID: <1243953404-31799-5-git-send-email-joerg.roedel@amd.com> X-Mailer: git-send-email 1.6.3.1 In-Reply-To: <1243953404-31799-1-git-send-email-joerg.roedel@amd.com> References: <1243953404-31799-1-git-send-email-joerg.roedel@amd.com> X-OriginalArrivalTime: 02 Jun 2009 14:36:48.0016 (UTC) FILETIME=[8F437100:01C9E38F] MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch adds the driver filter feature to the dma-debug documentation. Signed-off-by: Joerg Roedel --- Documentation/DMA-API.txt | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index d9aa43d..25fb8bc 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -704,12 +704,24 @@ this directory the following files can currently be found: The current number of free dma_debug_entries in the allocator. + dma-api/driver-filter + You can write a name of a driver into this file + to limit the debug output to requests from that + particular driver. Write an empty string to + that file to disable the filter and see + all errors again. + If you have this code compiled into your kernel it will be enabled by default. If you want to boot without the bookkeeping anyway you can provide 'dma_debug=off' as a boot parameter. This will disable DMA-API debugging. Notice that you can not enable it again at runtime. You have to reboot to do so. +If you want to see debug messages only for a special device driver you can +specify the dma_debug_driver= parameter. This will enable the +driver filter at boot time. The debug code will only print errors for that +driver afterwards. This filter can be disabled or changed later using debugfs. + When the code disables itself at runtime this is most likely because it ran out of dma_debug_entries. These entries are preallocated at boot. The number of preallocated entries is defined per architecture. If it is too low for you -- 1.6.3.1