Re: [PATCH] watchdog: allow WATCHDOG_PRETIMEOUT_GOV_SEL=y

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

On 10/17/26 15:27, Dmitry Voytik wrote:
> On Sat, Oct 17, 2026 at 11:42 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On 10/17/26 08:59, Dmitry Voytik wrote:
>>> Hi Guenter,
>>>
>>> Thanks for reviewing the patch!
>>>
>>> On Fri, Oct 16, 2026 at 8:21 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>>>
>>>> On 10/4/26 14:37, Dmitry Voytik wrote:
>>>>> Fix the issue when WATCHDOG_PRETIMEOUT_GOV_SEL can't be set to =y,
>>>>> and always is =m.
>>>>>
>>>>> The issues can be reproduced with the following steps:
>>>>>         make mrproper
>>>>>         make defconfig
>>>>>         ./scripts/config \
>>>>>           -e WATCHDOG_CORE \
>>>>>           -e WATCHDOG_PRETIMEOUT_GOV \
>>>>>           -e WATCHDOG_PRETIMEOUT_GOV_SEL \
>>>>>           --refresh
>>>>>         make olddefconfig
>>>>>         make mod2yesconfig
>>>>>
>>>>>         grep '=m$' .config
>>>>> returns only CONFIG_WATCHDOG_PRETIMEOUT_GOV_SEL as module:
>>>>>         CONFIG_WATCHDOG_PRETIMEOUT_GOV_SEL=m
>>>>>
>>>>> "make menuconfig" doesn't let it to be switched from =m to =y either.
>>>>>
>>>>
>>>> This does not explain what the problem actually is that is supposed
>>>> to be solved with this patch. Since this is just a selector used to
>>>> enable other configurations, and the configuration option does not
>>>> result in any packages built, "WATCHDOG_PRETIMEOUT_GOV_SEL can't be
>>>> set to =y" on its own is not a problem.
>>>
>>> The issue is that
>>>     make mod2yesconfig
>>> doesn't work as expected. Help says "Change answers from mod to yes if
>>> possible".
>>
>> This does say "If possible".
>>
>>> I might have misunderstood it, but I thought all configs should be =y
>>> for this make target.
>>>
>>
>> $ make allmodconfig
>> $ make mod2yesconfig
>> $ grep =m .config | wc -l
>> 51
>>
>> Not really.
>>
>>> Maybe a dumb question, but why does only this config have " default m"
>>> and others use
>>> "default WATCHDOG_CORE"? Does it have some special meaning with "default m"?
>>>
>>
>> Again, this configuration option is only used to set the (default) value
>> for the watchdog pretimeout governor, and the "=m" states that the default
>> should be WATCHDOG_PRETIMEOUT_GOV_PANIC=m, not =WATCHDOG_CORE.
> 
> This doesn't explain why it's =m by default.
> 
>>> I want to have no modules and still not disable the module load
>>> ability, and it annoys me
>>> that some configs don't allow "=y" :-) otherwise when I do
>>>    grep '=m$' .config
>>> I need to remember that CONFIG_WATCHDOG_PRETIMEOUT_GOV_SEL is a special case.
>>>
>>> FYI, for Arch Linux based config, only
>>> CONFIG_WATCHDOG_PRETIMEOUT_GOV_SEL pops up with =m.
>>> A fix for the same issue with CONFIG_TDX_HOST_SERVICES seems to be accepted:
>>> https://lore.kernel.org/lkml/as04AoNxjzlvh-K8@thinkstation/
>> You are comparing apples with oranges. That commit states:
>>
>>     Fix the issue when the driver always gets compiled as a module.
>>
>> There is no module that can or will be compiled based on
>> WATCHDOG_PRETIMEOUT_GOV_SEL.
> 
> Sure, I understand that. What is the semantic meaning of making it by
> default =m? And why can't I make it =y?
> I understand the build artifacts are the same, but I'm curious why =m?
> Why WATCHDOG_PRETIMEOUT_GOV_PANIC is not =m by default?
> Thanks for the explanation in advance!
> 

The idea is to build WATCHDOG_PRETIMEOUT_GOV_PANIC as module
by default. There is no "why" to answer. Why build anything as module
by default ? Are you going to question all those 478 default=m
configurations in the kernel ?

You still do not explain what actual problem you are trying to fix,
except that WATCHDOG_PRETIMEOUT_GOV_SEL can't be set to =y, which is
not a problem. The only problem I can see is that you don't like it,
which is not a reason for making any changes.

Guenter