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Thu, 08 Sep 2022 23:22:22 -0700 (PDT) X-Gm-Message-State: ACgBeo007AcRwlZjpeJmtlRcVd3aTq82scutwMi5a1MuARz7E+NsKxpK jcrjNNf6O8REW0OvR0TySIztO1XM62OU0dOpDYE= X-Google-Smtp-Source: AA6agR5EfzPia/RtqfbgAaGxxK9GzsmSY41Hz6mLA8v9uVa6Dj7ot+FeljQw/MpvxviU07INWGgyx2GDfngU3/ZEkp4= X-Received: by 2002:a05:6870:c58b:b0:10b:d21d:ad5e with SMTP id ba11-20020a056870c58b00b0010bd21dad5emr3918880oab.287.1662704541192; Thu, 08 Sep 2022 23:22:21 -0700 (PDT) MIME-Version: 1.0 References: <20220908104337.11940-1-lukas.bulwahn@gmail.com> <20220908104337.11940-2-lukas.bulwahn@gmail.com> In-Reply-To: <20220908104337.11940-2-lukas.bulwahn@gmail.com> From: Masahiro Yamada Date: Fri, 9 Sep 2022 15:21:44 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/6] arm: make config ARM_PATCH_PHYS_VIRT visible with EXPERT To: Lukas Bulwahn Cc: Russell King , linux-arm-kernel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , X86 ML , Mauro Carvalho Chehab , Linux Media Mailing List , Peter Chen , Greg Kroah-Hartman , linux-usb , Andrew Morton , Mike Rapoport , Linux Memory Management List , Linux Kbuild mailing list , kernel-janitors@vger.kernel.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662704545; a=rsa-sha256; cv=none; b=7W10eSkq1woHWYU6MreRcx+DrUygCHGrPsrnijcUxzxUIF1uF7YAxEbNycvCiu6wFHY2td vgw4ULwPCanosef3AvJTPtkWad2B6m1lJBqx/QnzOnjpB90/cOT6eI9gmtMjrZR3CPkrNA iZhcBppiKpToNVxvA8GpVoml+UAHTdU= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=nifty.com header.s=dec2015msa header.b=AnqLwOKS; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=softfail (imf04.hostedemail.com: 210.131.2.83 is neither permitted nor denied by domain of masahiroy@kernel.org) smtp.mailfrom=masahiroy@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662704545; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5gq83gYMVKdRU9r4hYVd7D4iDUbndUfSB3Fa4VRbM4A=; b=qZSOjJ09uBu14+WM6H6/I8+N45xkMuPl+78S+jkEY1QDtoiCWCliYZjiDTI5l6oxS1/3JN C7dTn0Wr3haggidktL7vCujl05jpD+XXmC54QbrWwNmVpFVsm6epUxB2yHqRLavbh3rxgv xvZ3R8YD2cdrudbpNSwI3HOBgPfIgfo= X-Stat-Signature: ydxio8em6ec99d6n5n5mkeo1acz6qywm X-Rspamd-Queue-Id: 6D38A4007C X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=nifty.com header.s=dec2015msa header.b=AnqLwOKS; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=softfail (imf04.hostedemail.com: 210.131.2.83 is neither permitted nor denied by domain of masahiroy@kernel.org) smtp.mailfrom=masahiroy@kernel.org X-Rspamd-Server: rspam12 X-HE-Tag: 1662704545-74036 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Sep 8, 2022 at 7:43 PM Lukas Bulwahn wrote: > > Commit 6a108a14fa35 ("kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT") > introduces CONFIG_EXPERT to carry the previous intent of CONFIG_EMBEDDED > and just gives that intent a much better name. That has been clearly a good > and long overdue renaming, and it is clearly an improvement to the kernel > build configuration that has shown to help managing the kernel build > configuration in the last decade. > > However, rather than bravely and radically just deleting CONFIG_EMBEDDED, > this commit gives CONFIG_EMBEDDED a new intended semantics, but keeps it > open for future contributors to implement that intended semantics: > > A new CONFIG_EMBEDDED option is added that automatically selects > CONFIG_EXPERT when enabled and can be used in the future to isolate > options that should only be considered for embedded systems (RISC > architectures, SLOB, etc). > > Since then, this CONFIG_EMBEDDED implicitly had two purposes: > > - It can make even more options visible beyond what CONFIG_EXPERT makes > visible. In other words, it may introduce another level of enabling the > visibility of configuration options: always visible, visible with > CONFIG_EXPERT and visible with CONFIG_EMBEDDED. > > - Set certain default values of some configurations differently, > following the assumption that configuring a kernel build for an > embedded system generally starts with a different set of default values > compared to kernel builds for all other kind of systems. > > Considering the first purpose, at the point in time where CONFIG_EMBEDDED > was renamed to CONFIG_EXPERT, CONFIG_EXPERT already made 130 more options > become visible throughout all different menus for the kernel configuration. > Over the last decade, this has gradually increased, so that currently, with > CONFIG_EXPERT, roughly 170 more options become visible throughout all > different menus for the kernel configuration. In comparison, currently with > CONFIG_EMBEDDED enabled, just seven more options are visible, one in x86, > one in arm, and five for the ChipIdea Highspeed Dual Role Controller. > > As the numbers suggest, these two levels of enabling the visibility of even > more configuration options---beyond what CONFIG_EXPERT enables---never > evolved to a good solution in the last decade. In other words, this > additional level of visibility of configuration option with CONFIG_EMBEDDED > compared to CONFIG_EXPERT has since its introduction never become really > valuable. It requires quite some investigation to actually understand what > is additionally visible and it does not differ significantly in complexity > compared to just enabling CONFIG_EXPERT. This CONFIG_EMBEDDED---or any > other config to show more detailed options beyond CONFIG_EXPERT---is > unlikely to be valuable unless somebody puts significant effort in > identifying how such visibility options can be properly split and creating > clear criteria, when some config option is visible with CONFIG_EXPERT and > when some config option is visible only with some further option enabled > beyond CONFIG_EXPERT, such as CONFIG_EMBEDDED attempted to do. For now, it > is much more reasonable to simply make those additional seven options that > visible with CONFIG_EMBEDDED, visible with CONFIG_EXPERT, and then remove > CONFIG_EMBEDDED. If anyone spends significant effort in structuring the > visibility of config options, they may re-introduce suitable new config > options simply as they see fit. > > Make the config ARM_PATCH_PHYS_VIRT visible when CONFIG_EXPERT is enabled. > > Signed-off-by: Lukas Bulwahn Reviewed-by: Masahiro Yamada > --- > arch/arm/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 4adfa5dd3556..4b212ab1b281 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -243,7 +243,7 @@ config ARCH_MTD_XIP > bool > > config ARM_PATCH_PHYS_VIRT > - bool "Patch physical to virtual translations at runtime" if EMBEDDED > + bool "Patch physical to virtual translations at runtime" if EXPERT > default y > depends on !XIP_KERNEL && MMU > help > -- > 2.17.1 > -- Best Regards Masahiro Yamada