Re: [PATCH] clocksource: timer-tegra186: Enable WDT at probe

[Jon Hunter]

On 03/07/2025 07:55, Thierry Reding wrote:
> On Mon, Jun 30, 2025 at 04:31:35PM +0530, Kartik Rajput wrote:
> > Currently, if the system crashes or hangs during kernel boot before
> > userspace initializes and configures the watchdog timer, then the
> > watchdog won’t be able to recover the system as it’s not running. This
> > becomes crucial during an over-the-air update, where if the newly
> > updated kernel crashes on boot, the watchdog is needed to reset the
> > device and boot into an alternative system partition. If the watchdog
> > is disabled in such scenarios, it can lead to the system getting
> > bricked.
> >
> > Enable the WDT during driver probe to allow recovery from any crash/hang
> > seen during early kernel boot. Also, disable interrupts once userspace
> > starts pinging the watchdog.
> >
> > Signed-off-by: Kartik Rajput <kkartik@xxxxxxxxxx>
> > ---
> >   drivers/clocksource/timer-tegra186.c | 42 ++++++++++++++++++++++++++++
> >   1 file changed, 42 insertions(+)
>
> This seems dangerous to me. It means that if the operating system
> doesn't start some sort of watchdog service in userspace that pings the
> watchdog, the system will reboot 120 seconds after the watchdog probe.


I don't believe that will happen with this change. The kernel will 
continue to pet the watchdog until userspace takes over with this 
change. At least that is my understanding.

Jon

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