Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759260Ab2FFXEE (ORCPT ); Wed, 6 Jun 2012 19:04:04 -0400 Received: from g1t0027.austin.hp.com ([15.216.28.34]:23307 "EHLO g1t0027.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994Ab2FFXEC (ORCPT ); Wed, 6 Jun 2012 19:04:02 -0400 Subject: Re: [PATCH] Disable Bus Master on PCI device shutdown From: Khalid Aziz To: Myron Stowe Cc: Matthew Garrett , linux-kernel@vger.kernel.org, bhelgaas@google.com, linux-pci@vger.kernel.org, "Eric W. Biederman" In-Reply-To: References: <20120427190033.GA17588@ldl.usa.hp.com> <20120606135009.GB1517@srcf.ucam.org> <1338999463.25761.630.camel@lyra> <20120606162703.GA6779@srcf.ucam.org> <1339003956.25761.667.camel@lyra> <20120606174202.GA8750@srcf.ucam.org> <1339006060.25761.689.camel@lyra> Content-Type: text/plain; charset="UTF-8" Date: Wed, 06 Jun 2012 17:03:59 -0600 Message-ID: <1339023839.25761.764.camel@lyra> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1665 Lines: 40 On Wed, 2012-06-06 at 14:16 -0600, Myron Stowe wrote: > Hay Khalid, > > I've been following this discussion but still do not understand what the > perceived correct fix is for the situation you were originally trying to > circumvent - namely, stopping NIC devices from triggering DMA activity > upon receipt of an incoming packet. > > From the discussion it sounds like a driver, upon shutdown, can end > all active I/O > clearing the I/O queue, and also (?) shut down its DMA engine, and may > also go as far as disabling the Bus Master bit. > > What was occurring in the original issue - was the driver in question not > shutting down its DMA engine for some, possibly valid, reason? > > Thanks, > Myron Hi Myron, The last driver issue with kexec was reported on kexec mailing list in July of last year and that was with qla driver. From what H Peter Anvin described, the driver left DMA engine running. For the issue I found on an ia64 platform, it was so many years ago that you are now taxing my old and decrepit memory :) I am digging through old internal bug reports and will let you know once I find that original bug report. ==================================================================== Khalid Aziz Unix Systems Lab (970)898-9214 Hewlett-Packard khalid.aziz@hp.com Fort Collins, CO -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/