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).
I think it's expected that the firmware support a crash dump mechanism of some kind. But if we're talking about firmware support, then why bother with the panic() in the first place?
Is there reason to believe that this all won't work on arm64 ?
No, but I'm still trying to figure out why pre-timeout is valuable. If we don't disable WS1, then we risk having the hardware reset before we can take advantage of what the panic() offers. In which case, what's the point of pre-timeout?
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