Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver
From: Fu Wei <hidden>
Date: 2015-09-15 03:16:32
Also in:
linux-watchdog, lkml
Hi Jon, On 11 September 2015 at 06:45, Jon Masters [off-list ref] wrote:
On 06/03/2015 02:53 PM, Timur Tabi wrote:quoted
On 06/03/2015 01:25 PM, Guenter Roeck wrote:quoted
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?quoted
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