linux-kernel - Re: Q: Kconfig: 'If unsure, say N'

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Message-Id: <D5L3IQFBCNBQ.1Z5OB2COPA7C5@cknow.org>
Date: Wed, 13 Nov 2024 14:47:12 +0100
From: "Diederik de Haas" <didi.debian@...ow.org>
To: "Sudeep Holla" <sudeep.holla@....com>
Cc: <linux-kernel@...r.kernel.org>, <linux-rockchip@...ts.infradead.org>,
 "Shawn Lin" <shawn.lin@...k-chips.com>
Subject: Re: Q: Kconfig: 'If unsure, say N'

Thanks for your response.

On Tue Nov 12, 2024 at 6:46 AM CET, Sudeep Holla wrote:
> On Fri, Nov 08, 2024 at 03:39:30PM +0100, Diederik de Haas wrote:
> > In quite a number of Kconfig help text entries I see this:
> > "If unsure, say N."
> >
> > But that raises the question: How can I be sure?
>
> If you don't know about the feature and it is not having any user-interface
> why do you want to enable it. You must understand the feature to enable it
> and use it IMO.

Ok, understood.

> You seem to contradict yourself here. If you have understood the help
> text and think it is useful, it seems to me as an indication that you
> are not unsure really. So you can enable it if you want TBH.
>
> > Not to discuss these specifically, but just for illustration:
> > ``drivers/firmware/arm_scmi/transports/Kconfig`` has this
> > option: ``ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE``
> > which IIUC enables an *optional* feature for an atomic transaction.
> >
>
> "If you want the SCMI SMC based transport to operate in atomic
> mode, avoiding any kind of sleeping behaviour for selected
> transactions on the TX path, answer Y.
>
> Enabling atomic mode operations allows any SCMI driver using this
> transport to optionally ask for atomic SCMI transactions and operate
> in atomic context too, at the price of using a number of busy-waiting
> primitives all over instead."
>
> So you read the above text, understood and find it useful. You must be
> not unsure of this feature then, so what does that text bother you.

In this case I was wondering whether this was related to Table 1 in
"Power and Performance Management using Arm SCMI Specification"
whitepaper.
And I do think that I understand most of the Help text, but I'm not/less
sure about the part starting with "at the price of ...".

> It is just a caution to users who are just build and not looked at the
> code, or have no idea about the feature or doesn't understand the help
> text.

And my question was exactly about "just a caution", which raises the
question with me "caution for what?" ... which is an unspecified risk.
So to be on the safe side, I will not enable modules with "If unsure,
say N" unless I fully understand the source code.

Cheers,
  Diederik

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