Re: [PATCH v4 5/7] Watchdog: introduce ARM SBSA watchdog driver

[Fu Wei]

Hi Guenter,


On 4 June 2015 at 02:25, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> On Wed, Jun 03, 2015 at 01:16:41PM -0500, Timur Tabi wrote:
>> On 06/01/2015 11:05 PM, fu.wei@xxxxxxxxxx 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).

yes, you are right , thanks for explaining this.

>
> Is there reason to believe that this all won't work on arm64 ?

I don't think there is a reason.

>
> Thanks,
> Guenter



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Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
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