Re: [PATCH] watchdog: allow WATCHDOG_PRETIMEOUT_GOV_SEL=y

[Guenter Roeck]

On 10/17/26 15:27, Dmitry Voytik wrote:
> On Sat, Oct 17, 2026 at 11:42 PM Guenter Roeck <linux@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> 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