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

    Jon.



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