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Message-ID: <CAK7LNAR89KNWVbUBZiOP1Yv7V-0rGO3L3xKvza9hnHjn0DFJcw@mail.gmail.com>
Date: Wed, 28 Mar 2018 01:39:13 +0900
From: Masahiro Yamada <yamada.masahiro@...ionext.com>
To: Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Cc: Sam Ravnborg <sam@...nborg.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Arnd Bergmann <arnd@...db.de>, Ulf Magnusson <ulfalizer@...il.com>,
Kees Cook <keescook@...omium.org>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Luis R . Rodriguez" <mcgrof@...nel.org>,
Nicolas Pitre <nico@...aro.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>,
Emese Revfy <re.emese@...il.com>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 00/21] kconfig: move compiler capability tests to Kconfig
2018-03-27 14:29 GMT+09:00 Masahiro Yamada <yamada.masahiro@...ionext.com>:
>
> Here is v2 to start to move compiler capability tests to Kconfig.
>
> V1:
> https://lkml.org/lkml/2018/2/16/610
>
> I brushed up the implementation even more.
>
> Major changes for v2:
> [1] Environments and functions are expanded in the lexer (zconf.l)
> The parser (zconf.y) receives expanded tokens. This simplifies
> the implementation.
>
> [2] Implement only one built-in function 'shell'. This returns
> stdout from the command. We need something to return 'y' or 'n'.
> This is now implemented as a macro 'success'.
>
> [3] Macros (user-defined function) are defined by 'macro' keyword
> instead of string type symbol.
>
> ex1) macro success $(shell ($(1) && echo y) || echo n)
> ex2) macro cc-option $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)
>
> My plan for v3
> --------------
>
> The MW is approaching, but I'd like to make it more lovely if
> I have some time.
>
> While I was writing these patches, I noticed a kind of similarity
> between Makefile and Kconfig.
>
> Makefile can define variables and functions to do text processing
> during the parse phase. After parsing, it builds up dependency
> graph, and moves on to the execution phase. Then, it generates
> objects as needed by checking time-stamps.
>
> [Makefile]
>
> OBJ := foo.o
> SRC := foo.c
> CC := gcc
>
> $(OBJ): $(SRC)
> $(CC) -c -o $(OBJ) $(SRC)
>
> [Makefile after text processing]
>
> foo.o: foo.c
> gcc -c -o foo.o foo.c
>
> Now, we are adding tools for text processing to Kconfig. Functions
> are statically expanded by the lexer. After all source files are
> parsed, Kconfig moves on to the evaluation phase. Then, users can
> tweak symbol values from menus.
>
> So, we should be able to describe Kconfig like follows:
>
> [Kconfig]
>
> MY_SYMBOL := CC_STACKPROTECTOR
> MY_PROMPT := "Stackprotector"
> success = $(shell ($(1) && echo y) || echo n)
> cc-option = $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)
>
> config $(MY_SYMBOL)
> bool $(MY_PROMPT)
> depends on $(cc-option -fstack-protector)
>
> [Kconfig after text processing]
>
> config CC_STACKPROTECTOR
> bool "Stackptector"
> depends on y
>
> So, I think it is better to use '=' assignment for defining functions.
> I will remove the 'macro' keyword.
> Also, support variables. A variable is a function with no argument.
> So, it will be easy to implement it as a sub-set of function feature.
> It is better to support two flavors of assignments, '=' and ':=' as well.
>
> Masahiro Yamada (21):
> kbuild: remove kbuild cache
> kbuild: remove CONFIG_CROSS_COMPILE support
> kconfig: move and rename sym_expand_string_value()
> kconfig: reference environments directly and remove 'option env='
> syntax
> kconfig: remove string expansion in file_lookup()
> kconfig: remove string expansion for mainmenu after yyparse()
> kconfig: add function support and implement 'shell' function
> kconfig: replace $UNAME_RELEASE with function call
> kconfig: add 'macro' keyword to support user-defined function
> kconfig: add 'success' and 'cc-option' macros
> stack-protector: test compiler capability in Kconfig and drop AUTO
> mode
> kconfig: show compiler version text in the top comment
> kconfig: add CC_IS_GCC and GCC_VERSION
> kconfig: add CC_IS_CLANG and CLANG_VERSION
> gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
> kcov: imply GCC_PLUGINS and GCC_PLUGIN_SANCOV instead of select'ing
> them
> gcc-plugins: always build plugins with C++
> gcc-plugins: move GCC version check for PowerPC to Kconfig
> gcc-plugins: test GCC plugin support in Kconfig
> gcc-plugins: enable GCC_PLUGINS for COMPILE_TEST
> arm64: move GCC version check for ARCH_SUPPORTS_INT128 to Kconfig
>
> Documentation/kbuild/kconfig-language.txt | 8 --
> Kconfig | 4 +-
> Makefile | 103 ++------------
> arch/Kconfig | 37 ++---
> arch/arm64/Kconfig | 1 +
> arch/arm64/Makefile | 2 -
> arch/powerpc/Kconfig | 2 +-
> arch/sh/Kconfig | 4 +-
> arch/sparc/Kconfig | 4 +-
> arch/tile/Kconfig | 2 +-
> arch/um/Kconfig.common | 4 -
> arch/x86/Kconfig | 12 +-
> arch/x86/um/Kconfig | 4 +-
> init/Kconfig | 44 +++---
> kernel/gcov/Kconfig | 17 +--
> kernel/gcov/Makefile | 2 -
> lib/Kconfig.debug | 7 +-
> scripts/Kbuild.include | 101 ++------------
> scripts/Makefile.gcc-plugins | 95 ++++---------
> scripts/clang-version.sh | 24 ++--
> scripts/gcc-plugin.sh | 37 +----
> scripts/gcc-plugins/Makefile | 15 +-
> scripts/gcc-x86_32-has-stack-protector.sh | 7 +-
> scripts/gcc-x86_64-has-stack-protector.sh | 5 -
> scripts/kconfig/confdata.c | 31 +---
> scripts/kconfig/env.c | 95 +++++++++++++
> scripts/kconfig/function.c | 225 ++++++++++++++++++++++++++++++
> scripts/kconfig/kconf_id.c | 1 -
> scripts/kconfig/lkc.h | 9 +-
> scripts/kconfig/lkc_proto.h | 7 +-
> scripts/kconfig/menu.c | 3 -
> scripts/kconfig/symbol.c | 109 ---------------
> scripts/kconfig/util.c | 96 ++++++++++---
> scripts/kconfig/zconf.l | 51 ++++++-
> scripts/kconfig/zconf.y | 35 ++---
> 35 files changed, 608 insertions(+), 595 deletions(-)
> create mode 100644 scripts/kconfig/env.c
> create mode 100644 scripts/kconfig/function.c
>
> --
> 2.7.4
>
> --
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For convenience, the whole of this series is available at
the following branch.
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
kconfig-shell-v2
--
Best Regards
Masahiro Yamada
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