From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [Fastboot] [RFC] [PATCH 2/2] kdump: cciss driver initialization issue fix Date: Mon, 26 Jun 2006 10:38:09 -0600 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:53934 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1750782AbWFZQig (ORCPT ); Mon, 26 Jun 2006 12:38:36 -0400 In-Reply-To: (Mike Miller's message of "Mon, 26 Jun 2006 11:13:32 -0500") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Miller, Mike (OS Dev)" Cc: vgoyal@in.ibm.com, Maneesh Soni , Andrew Morton , Neela.Kolli@engenio.com, linux-scsi@vger.kernel.org, fastboot@lists.osdl.org, linux-kernel@vger.kernel.org "Miller, Mike (OS Dev)" writes: > All, > Sorry to come in late and top post. I've been out of the office and I'm > trying to get to the gist of this issue. > Exactly what is the problem? I'm not familiar with kdump so I don't have > a clue about what's going on. > There are a couple of reset features supported by _some_ cciss > controllers. I'd have to go back to the open spec to see whats in the > public domain. We're trying to get the open spec updated and more > complete but we're waiting on the lawyers. :( kdump or taking crash dumps using the kexec on panic mechanism could be called a drivers worst nightmare. In the latest distros this is becoming the way crash dump style information is captured. Because the initial kernel is broken we do a jump into another kernel that is sufficient to record a crash dump. That second kernel initializes the hardware from whatever random state the first kernel left the drivers in. That first kernel is not permitted to do any device shutdown activities. The problem is that a command the running instance of the driver did not initiate completes. At least if I read Vivek patch 2/2 correctly. So we have three options. - reset the card during initialization. - handle the case of a command we did not initiate completing. - mark the driver/card as impossibly hopeless for use in a crash dump scenario. Eric