Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261602AbVDZPjq (ORCPT ); Tue, 26 Apr 2005 11:39:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261592AbVDZPj2 (ORCPT ); Tue, 26 Apr 2005 11:39:28 -0400 Received: from colo.lackof.org ([198.49.126.79]:20955 "EHLO colo.lackof.org") by vger.kernel.org with ESMTP id S261576AbVDZPjW (ORCPT ); Tue, 26 Apr 2005 11:39:22 -0400 Date: Tue, 26 Apr 2005 09:41:49 -0600 From: Grant Grundler To: Alan Stern Cc: Alexander Nyberg , Greg KH , Amit Gud , linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, akpm@osdl.org, jgarzik@pobox.com, cramerj@intel.com, USB development list Subject: Re: [PATCH] PCI: Add pci shutdown ability Message-ID: <20050426154149.GA2612@colo.lackof.org> References: <1114458325.983.17.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Home-Page: http://www.parisc-linux.org/ User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1223 Lines: 26 On Mon, Apr 25, 2005 at 04:14:13PM -0400, Alan Stern wrote: > > Not sure what you mean by "make kexec work nicer" but if it is because > > some devices don't work after a kexec I have some objections. > > That was indeed the reason, at least in my case. The newly-rebooted > kernel doesn't work too well when there are active devices, with no driver > loaded, doing DMA and issuing IRQs because they were never shut down. This is also a problem at "normal" boot time. BIOS may leave devices still doing DMA if BIOS (or the arch equivalent) was using the device. This problem is obvious for systems with an IOMMU (e.g. parisc). See drivers/parisc/sba_iommu.c for an example of where I try to deal with active DMA at boot time *before* PCI bus walks have occurred. Masking IRQs is trivial in comparison to dealing with active DMA. > > What about the kexec-on-panic? Same problem - just much more likely to hit the issue and completely crash the box or corrupt memory. grant - 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/