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[209.85.208.176]) by smtp.gmail.com with ESMTPSA id h26sm4401771lfj.20.2020.08.07.08.54.41 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 07 Aug 2020 08:54:41 -0700 (PDT) Received: by mail-lj1-f176.google.com with SMTP id 185so2716039ljj.7 for ; Fri, 07 Aug 2020 08:54:41 -0700 (PDT) X-Received: by 2002:a2e:92d0:: with SMTP id k16mr1055600ljh.70.1596815680797; Fri, 07 Aug 2020 08:54:40 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Linus Torvalds Date: Fri, 7 Aug 2020 08:54:24 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] RESEND: thermal for v5.9-rc1 To: Daniel Lezcano Cc: Zhang Rui , Amit Kucheria , Andrzej Pietrasiewicz , Colin King , Shawn Guo , Lukasz Luba , Sumeet Pawnikar , Henry Yen , Thierry Reding , Linux Kernel Mailing List , Linux PM mailing list , Marian-Cristian Rotariu Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 7, 2020 at 2:40 AM Daniel Lezcano wrote: > > It defaults to 'y' because the previous (but unused) implementation was > unconditionally compiled-in and because of the thermal users needs. > > Is default=y wrong given this history? One million percent wrong. The fact that the old implementation was never used just shows that it's not so important, and it shouldn't be default 'y'. Not having it doesn't break anything. And the new implementation presumably isn't even compatible with the old format also means that it shouldn't be default 'y'. Building it in wouldn't help anyway. And the fact that _some_ users might want it does not mean that it should be default 'y', because those users presumably _know_ they want it. IOW, defaulting to 'y' is just wrong in every possible way. This is not some kind of "to maintain compatibility and not break existing users we should enable this" kind of thing. And it's not some kind of "everybody should have it" thing either, since presumably nobody has the user-space support for it anyway. It's something that a new distro would enable _if_ they actually end up supporting the user space. Not something the kernel should enable "just because". Really: "default y" is _wrong_. Every developer thinks that _their_ code is so magical and special that everybody should run it. And every developer is almost always wrong. Unless you have a "not having this will break existing users", you don't do it. Linus