From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756324AbbFCSZS (ORCPT ); Wed, 3 Jun 2015 14:25:18 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:40345 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752961AbbFCSZK (ORCPT ); Wed, 3 Jun 2015 14:25:10 -0400 Date: Wed, 3 Jun 2015 11:25:03 -0700 From: Guenter Roeck To: Timur Tabi Cc: fu.wei@linaro.org, Suravee.Suthikulpanit@amd.com, linaro-acpi@lists.linaro.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, tekkamanninja@gmail.com, graeme.gregory@linaro.org, al.stone@linaro.org, hanjun.guo@linaro.org, ashwin.chaugule@linaro.org, arnd@arndb.de, vgandhi@codeaurora.org, wim@iguana.be, jcm@redhat.com, leo.duran@amd.com, corbet@lwn.net, mark.rutland@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, rjw@rjwysocki.net Subject: Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver Message-ID: <20150603182503.GD6460@roeck-us.net> References: <=fu.wei@linaro.org> <1433217907-928-1-git-send-email-fu.wei@linaro.org> <1433217907-928-6-git-send-email-fu.wei@linaro.org> <556F4489.6030206@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <556F4489.6030206@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=0.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 03, 2015 at 01:16:41PM -0500, Timur Tabi wrote: > On 06/01/2015 11:05 PM, fu.wei@linaro.org wrote: > >+ if (wdd->pretimeout) > >+ /* The pretimeout is valid, go panic */ > >+ panic("SBSA Watchdog pre-timeout"); > > The problem with this is that WS1 will still occur. So a few seconds after > the panic() call, the hardware will reset. There won't be any time to debug > or log anything. > In general the idea here would be to use a crashdump kernel, which, when loaded, would reset the watchdog before it fires. This kernel would then write a core dump to a specified location. If arm64 doesn't support a crashdump kernel, it might still be possible to log the backtrace somewhere (eg in nvram using pstore if that is supported via acpi or efi). Is there reason to believe that this all won't work on arm64 ? Thanks, Guenter From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver Date: Wed, 3 Jun 2015 11:25:03 -0700 Message-ID: <20150603182503.GD6460@roeck-us.net> References: <=fu.wei@linaro.org> <1433217907-928-1-git-send-email-fu.wei@linaro.org> <1433217907-928-6-git-send-email-fu.wei@linaro.org> <556F4489.6030206@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <556F4489.6030206-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> Sender: linux-watchdog-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Timur Tabi Cc: fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, Suravee.Suthikulpanit-5C7GfCeVMHo@public.gmane.org, linaro-acpi-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tekkamanninja-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, graeme.gregory-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, al.stone-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, ashwin.chaugule-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, vgandhi-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org, jcm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, leo.duran-5C7GfCeVMHo@public.gmane.org, corbet-T1hC0tSOHrs@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org List-Id: devicetree@vger.kernel.org On Wed, Jun 03, 2015 at 01:16:41PM -0500, Timur Tabi wrote: > On 06/01/2015 11:05 PM, fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org wrote: > >+ if (wdd->pretimeout) > >+ /* The pretimeout is valid, go panic */ > >+ panic("SBSA Watchdog pre-timeout"); > > The problem with this is that WS1 will still occur. So a few seconds after > the panic() call, the hardware will reset. There won't be any time to debug > or log anything. > In general the idea here would be to use a crashdump kernel, which, when loaded, would reset the watchdog before it fires. This kernel would then write a core dump to a specified location. If arm64 doesn't support a crashdump kernel, it might still be possible to log the backtrace somewhere (eg in nvram using pstore if that is supported via acpi or efi). Is there reason to believe that this all won't work on arm64 ? Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html