Re: watchdog: how to enable?

[Guenter Roeck <linux@roeck-us.net>]

On 11/18/19 7:09 AM, Muni Sekhar wrote:
> On Mon, Nov 18, 2019 at 8:08 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>>
>> [-cc linux-pci (nothing here is PCI-specific)]
>>
>> On Sat, Nov 16, 2019 at 06:05:05AM +0530, Muni Sekhar wrote:
>>> My kernel is built with the following options:
>>>
>>> $ cat /boot/config-5.0.1 | grep NO_HZ
>>> CONFIG_NO_HZ_COMMON=y
>>> CONFIG_NO_HZ_IDLE=y
>>> # CONFIG_NO_HZ_FULL is not set
>>> CONFIG_NO_HZ=y
>>> CONFIG_RCU_FAST_NO_HZ=y
>>>
>>> I booted with watchdog enabled(nmi_watchdog=1) as given below:
>>>
>>> BOOT_IMAGE=/boot/vmlinuz-5.0.1
>>> root=UUID=f65454ae-3f1d-4b9e-b4be-74a29becbe1e ro debug
>>> ignore_loglevel console=ttyUSB0,115200 console=tty0 console=tty1
>>> console=ttyS2,115200 memmap=1M!1023M nmi_watchdog=1
>>> crashkernel=384M-:128M
>>>
>>> When the system is frozen or the kernel is locked up(I noticed that in
>>> this state kernel is not responding for ALT-SysRq-<command key>) but
>>> watchdog is not triggered. So I want to understand how to enable the
>>> watchdog timer and how to verify the basic watchdog functionality
>>> behavior?
>>
>> I don't know much about the watchdog, but I assume you've found these
>> already?
>>
>>    Documentation/admin-guide/lockup-watchdogs.rst
>>    Documentation/admin-guide/sysctl/kernel.rst
>>
>> Do you have CONFIG_HAVE_NMI_WATCHDOG=y?  (See arch/Kconfig)
> 
> I don’t have CONFIG_HAVE_NMI_WATCHDOG in kernel .config file.
> 

That would mean you don't have NMI in the first place. What is your
architecture ?

Guenter

> $cat /boot/config-5.0.1 | grep CONFIG_HAVE_NMI_WATCHDOG
> 
> But tried to enable CONFIG_HAVE_NMI_WATCHDOG via menuconfig, but could
> not able to find it. What is the role of CONFIG_HAVE_NMI_WATCHDOG?
> 
> Symbol: HAVE_NMI_WATCHDOG [=n]
> 
>                                              │
>    │ Type  : bool
> 
>                                                  │
>    │   Defined at arch/Kconfig:339
> 
>                                                  │
>    │   Depends on: HAVE_NMI [=y]
> 
>                                                  │
>    │   Selected by [n]:
> 
>                                                  │
>    │   - HAVE_HARDLOCKUP_DETECTOR_ARCH [=n]
> 
> 
>    │ Symbol: HAVE_HARDLOCKUP_DETECTOR_ARCH [=n]
> 
>                                                  │
>    │ Type  : bool
> 
>                                                  │
>    │   Defined at arch/Kconfig:346
> 
>                                                  │
>    │   Selects: HAVE_NMI_WATCHDOG [=n]
> 
> 
> 
> 
>