Re: iTCO_wdt watchdog on Asus P10S-WS motherboard FREEZES MOTHERBOARD COMPLETELY

[Mika Westerberg]

On Thu, Sep 08, 2016 at 07:01:09PM +0200, David Madore wrote:
> TL;DR: the iTCO_wdt watchdog on the Asus P10S-WS motherboard, instead
> of rebooting the machine, places the motherboard in a completely
> nonfunctional state, from which it can be revived only by a hard power
> cycle.  I suspect this is a BIOS bug: seeking advice on how/where to
> report this, and what to do generally.  Maybe Linux can work around?
> 
> 
> Dear list,
> 
> I have an Asus P10S-WS motherboard (Intel C236 chipset).  I have been
> trying to get the iTCO_wdt hardware watchdog to work (I have been
> successfully using this driver with similar Intel chipset based Asus
> motherboards before, and I know it to work reliably).  I am using
> Linux 4.7.3.
> 
> I trigger a reboot by killing (with kill -9) the wd_keepalive daemon
> once it has opened the watchdog device.
> 
> Sadly, it appears that on this motherboard, the watchdog does not
> reboot the machine (or at least, does not successfully reboot it).
> Instead, the machine enters a "frozen" state (fans spinning, screen
> black, all peripherals unresponsive) from which it cannot be woken up
> by pressing the reset button, or even the power button twice (the
> first press does turn the machine off, but it returns to the same
> nonfunctional state after power on).  Instead, power has to be cut
> completely, at the power supply level.
> 
> In this nonfunctional state, the Asus POST status display shows the
> number "62", which according to the motherboard manual is the code for
> "installation of the PCH runtime services" (I have no idea of what
> that means).
> 
> I suspect that this is a BIOS ^W UEFI bug and in no way Linux's fault.
> It could also be a hardware problem, a chipset bug, or something else.
> And even if it is a firmware bug, it is conceivable that there is a
> way to work around the problem from Linux.  So I ask for guidance from
> the wisdom of this list:
> 
> * Is there something Linux can do about the problem?
> 
> * Is there a chance some kernel developer knows someone at Asus and
>   can bring this problem to their attention?
> 
> * Can someone report success using the iTCO_wdt watchdog with other
>   motherboards having the same Intel C236 chipset?  (Note: for it to
>   work, the i2c_smbus module needs to be loaded: it took me a long
>   time to figure out.)
> 
> * Is all hope lost for my motherboard?  (I badly need a hardware
>   watchdog: if there is no way to get it to work on this motherboard,
>   I will need to buy a new one.)
> 
> Any suggestions are welcome (or even words of comfort :-).

Does the machine have WDAT ACPI table (see /sys/firmware/acpi/tables/*)?
If it does, you can try the new WDAT watchdog driver instead [1]. It
still uses the same hardware, though but via set of instructions
provided by the BIOS that should work (given the vendor has tested
it on Windows).

[1] http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1230607.html