From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752457AbbIODQc (ORCPT ); Mon, 14 Sep 2015 23:16:32 -0400 Received: from mail-oi0-f49.google.com ([209.85.218.49]:35356 "EHLO mail-oi0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752010AbbIODQ3 (ORCPT ); Mon, 14 Sep 2015 23:16:29 -0400 MIME-Version: 1.0 In-Reply-To: <55F207FD.2030007@redhat.com> 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> <20150603182503.GD6460@roeck-us.net> <556F4D29.1080001@codeaurora.org> <55F207FD.2030007@redhat.com> Date: Tue, 15 Sep 2015 11:16:28 +0800 Message-ID: Subject: Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver From: Fu Wei To: Jon Masters Cc: Timur Tabi , Guenter Roeck , Suravee Suthikulpanit , Linaro ACPI Mailman List , linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, LKML , linux-doc@vger.kernel.org, Wei Fu , G Gregory , Al Stone , Hanjun Guo , Ashwin Chaugule , Arnd Bergmann , Vipul Gandhi , Wim Van Sebroeck , Leo Duran , Jon Corbet , Mark Rutland , Catalin Marinas , Will Deacon , Rafael Wysocki Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jon, On 11 September 2015 at 06:45, Jon Masters wrote: > On 06/03/2015 02:53 PM, Timur Tabi wrote: >> On 06/03/2015 01:25 PM, Guenter Roeck wrote: >>> 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. >> >> What is the mechanism for resetting the watchdog? The only code that >> knows about the hardware registers is this driver. Does the crashdump >> kernel call the watchdog stop function? >> >>> 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). > > Just to go back and explicitly answer this, arm64 does have support for > crashdump, using the standard kexec/kdump approach, exactly as on x86. > There's still some more work to be done to get the ACPI case fully > upstream (e.g. on X-Gene platforms such as the HP ProLiant Moonshot m400 > we need non-PSCI CPU parking protocol offlining when booting in > UEFI/ACPI mode), but it's what we are doing in RHEL(SA) and the goal is > to help clean up the remaining pieces upstream there. Great thanks for your info. I have tried kexec/kdump on a real aarch64 hardware, that works well. Although it's still under development and upstreaming, the support is there. After discussing with some kexec/kdump developer, I think this driver can cooperate with kexec/kdump. > > Jon. > -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fu Wei Subject: Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver Date: Tue, 15 Sep 2015 11:16:28 +0800 Message-ID: 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> <20150603182503.GD6460@roeck-us.net> <556F4D29.1080001@codeaurora.org> <55F207FD.2030007@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <55F207FD.2030007-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-watchdog-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jon Masters Cc: Timur Tabi , Guenter Roeck , Suravee Suthikulpanit , Linaro ACPI Mailman List , linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, LKML , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wei Fu , G Gregory , Al Stone , Hanjun Guo , Ashwin Chaugule , Arnd Bergmann , Vipul Gandhi , Wim Van Sebroeck , Leo Duran , Jon Corbet , Mark Rutland , Catalin Marinas , Will Deacon , Rafael Wysocki List-Id: devicetree@vger.kernel.org Hi Jon, On 11 September 2015 at 06:45, Jon Masters wrote: > On 06/03/2015 02:53 PM, Timur Tabi wrote: >> On 06/03/2015 01:25 PM, Guenter Roeck wrote: >>> 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. >> >> What is the mechanism for resetting the watchdog? The only code that >> knows about the hardware registers is this driver. Does the crashdump >> kernel call the watchdog stop function? >> >>> 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). > > Just to go back and explicitly answer this, arm64 does have support for > crashdump, using the standard kexec/kdump approach, exactly as on x86. > There's still some more work to be done to get the ACPI case fully > upstream (e.g. on X-Gene platforms such as the HP ProLiant Moonshot m400 > we need non-PSCI CPU parking protocol offlining when booting in > UEFI/ACPI mode), but it's what we are doing in RHEL(SA) and the goal is > to help clean up the remaining pieces upstream there. Great thanks for your info. I have tried kexec/kdump on a real aarch64 hardware, that works well. Although it's still under development and upstreaming, the support is there. After discussing with some kexec/kdump developer, I think this driver can cooperate with kexec/kdump. > > Jon. > -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 -- 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