On Wed, Oct 03, 2012 at 07:46:18PM +0200, Frederic Weisbecker wrote:
> > it in the kernel tree, unless we wanted people to use the option?
>
> A solution could be to add that option under CONFIG_DEBUG_KERNEL and specify
> that it must only be enabled by developers for specific reasons (overhead,
> security). CONFIG_PROVE_LOCKING falls into that category, right?
>
> We have CONFIG_RCU_USER_QS that is a specific case. It's an intermediate
> state
> before we implement a true CONFIG_NO_HZ_FULL. But the option is useless on
> its
> own for users. Worse, it introduces a real overhead. OTOH we want it to be
> upstream
> to make the development of full tickless feature more incremental.
>
> Perhaps we should put that under CONFIG_DEBUG_KERNEL.
Overloading an existing config option for something unrelated seems unpleasant
to me.
It will only take a few people to start doing this, before it turns into a
landslide
where everyone ends up with DEBUG_KERNEL set.
And what of people who already have DEBUG_KERNEL set ?
Just state what you wrote above in the kconfig.
Currently, RCU_USER_QS says nothing about the fact that it's work in progress.
The missing part that I don't have an answer for however, is what happens
when you deem this production ready? Distro maintainers won't notice the
kconfig text changing. But perhaps that's a good thing, and will lead to things
only being enabled when people explicitly ask for them in distros.
Alternatively, if you really do want to go the path of a new config option,
perhaps CONFIG_NOT_DISTRO_READY would spell things out more clearly.
EXPERIMENTAL is such a wasteland it would take too much manpower to audit
every case, and update accordingly, but scorching the earth and starting
afresh might be feasible.
Dave
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