2018-05-28 18:21 GMT+09:00 Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>: > > [Introduction] > > The motivation of this work is to move the compiler option tests to > Kconfig from Makefile. A number of kernel features require the > compiler support. Enabling such features blindly in Kconfig ends up > with a lot of nasty build-time testing in Makefiles. If a chosen > feature turns out unsupported by the compiler, what the build system > can do is either to disable it (silently!) or to forcibly break the > build, despite Kconfig has let the user to enable it. By moving the > compiler capability tests to Kconfig, Kconfig entries will be visible > only when they are available. > > [Major Changes in V5] > > V5 removed the complexity unnecessary for Kconfig. > > - In order to make the implementation simpler, I drop the lazy > argument expansion. > In V5, parameters are expanded before passed to a function. > (the same behavior as v3) > > - Replace 'warning', 'error' functions with 'warning-if', > 'error-if' functions. The new functions are effective > only when the condition part is 'y'. > > - In V4, '$' must be followed by '$' or '('. > '$$' meant an escaped '$'. > > V4 caused a build error for ARC architecture due to the > following line: > https://github.com/torvalds/linux/blob/v4.17-rc4/arch/arc/Kconfig#L252 > > Of course, we could rephrase "D$" to "D cache", but > I treaked the grammar a little bit. > > Kconfig decided to not support single-letter variable as in "$X". > Nor curly braces as in "${CC}" are not supported. > This means variable/function references in Kconfig always start > with "$(". > We can use '$' not followed by '(' as-is. > We do not need the "$$" escape sequence. > If necessary, we can use a trick to print '$(' verbatim. See below. > > - Fix a wrong behavior of simply expanded variables. > V4 expanded simply expanded variables when used, but it should not. > > For example, > > dollar := $ > X := 1 > Y := $(dollar)(X) > $(info,$(Y)) > > V5 prints '$(X)', not '1'. > > - Remove a space after a comma is $( ) context. > Actually, spaces do not matter in most cases. > > You can write either > > $(cc-option,-fstack-protector) > > or > > $(cc-option, -fstack-protector) > > In fact, both style co-exist in our Makefiles too. > However, there are some cases where they do matter. > > I remove spaces after commas for consistency. > If you are unsure, no-space-after-comma is always safe. > > [Major Changes in V4] > > - In V4, I slightly change the syntax of a function call. > I chose grammatical consistency and simplicity. > Anyway, Kconfig is deviating from Make behavior already. > > In v3, a function call looked like this: > > $(func-name arg1,arg2,arg3) > > In v4, a function is invoked like follows: > > $(func-name,arg1,arg2,arg3) > > The difference is that the function name and the first argument > are separated by a comma. > > - V3 supported single-letter variable like $X. > V4 dropped it because we do not need multiple ways to do the > same thing. > You must always enclose a variable name like $(X). > > - Support lazy argument expansion. This is necessary for implementing > 'if', 'and', 'or' functions as in Make. > > - Add more built-in functions: > 'if', 'error', 'filename', 'lineno' > > - Error out if a recursive variable references itself eventually. > For example, X = $(X) > ends up with a circular expansion. It must be terminated > since the expansion would continue eternally. > > - Update Documentation and unit-tests, accordingly. > > [Major Changes in V3] > > This version looks more like Make. > > - Use = operator instead of 'macro' keyword > to define a user-defined function. > > - 'Recursively expanded variable' is implemented as a side-effect. > A variable is a function with zero argument. > > - Support simply expanded variable which is defined by := operator > > - Support += operator. > Probably, this feature will be useful to accumulate compiler flags. > At least, Clang needs some prerequisite flags such as triplet > to test other compiler flags. > > - Support $(info ...) and $(warning ...) built-in functions, > which were useful while I was debugging this. > > - Add documentation > > - Add unit tests > > - Collect helpers to scripts/Kconfig.include > > [Old Versions] > > V4: https://lkml.org/lkml/2018/5/17/97 > V3: https://lkml.org/lkml/2018/4/13/37 > V2: https://lkml.org/lkml/2018/2/16/610 > V1: https://lkml.org/lkml/2018/2/16/610 > RFC: https://lkml.org/lkml/2018/2/8/429 > > > Masahiro Yamada (31): > kbuild: remove kbuild cache > kbuild: remove CONFIG_CROSS_COMPILE support > kconfig: reference environment variables directly and remove 'option > env=' > kconfig: remove string expansion in file_lookup() > kconfig: remove string expansion for mainmenu after yyparse() > kconfig: remove sym_expand_string_value() > kconfig: make default prompt of mainmenu less specific > kconfig: add built-in function support > kconfig: add 'shell' built-in function > kconfig: replace $(UNAME_RELEASE) with function call > kconfig: begin PARAM state only when seeing a command keyword > kconfig: support user-defined function and recursively expanded > variable > kconfig: support simply expanded variable > kconfig: support append assignment operator > kconfig: expand lefthand side of assignment statement > kconfig: add 'info', 'warning-if', and 'error-if' built-in functions > kconfig: add 'filename' and 'lineno' built-in variables > kconfig: error out if a recursive variable references itself > Documentation: kconfig: document a new Kconfig macro language > kconfig: test: add Kconfig macro language tests > kconfig: show compiler version text in the top comment > kconfig: add basic helper macros to scripts/Kconfig.include > stack-protector: test compiler capability in Kconfig and drop AUTO > mode > kconfig: add CC_IS_GCC and GCC_VERSION > kconfig: add CC_IS_CLANG and CLANG_VERSION > gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT > kcov: test compiler capability in Kconfig and correct dependency > gcc-plugins: move GCC version check for PowerPC to Kconfig > gcc-plugins: test plugin support in Kconfig and clean up Makefile > gcc-plugins: allow to enable GCC_PLUGINS for COMPILE_TEST > Documentation: kconfig: add recommended way to describe compiler > support > > Documentation/kbuild/kconfig-language.txt | 26 +- > Documentation/kbuild/kconfig-macro-language.txt | 242 +++++++++ > Kconfig | 10 +- > MAINTAINERS | 3 +- > Makefile | 105 +--- > arch/Kconfig | 49 +- > arch/powerpc/Kconfig | 2 +- > arch/sh/Kconfig | 4 +- > arch/sparc/Kconfig | 4 +- > arch/um/Kconfig.common | 4 - > arch/x86/Kconfig | 15 +- > arch/x86/um/Kconfig | 10 +- > init/Kconfig | 40 +- > kernel/gcov/Kconfig | 17 +- > kernel/gcov/Makefile | 2 - > lib/Kconfig.debug | 11 +- > scripts/Kbuild.include | 101 +--- > scripts/Kconfig.include | 30 ++ > scripts/Makefile.gcc-plugins | 91 +--- > scripts/Makefile.kcov | 10 +- > scripts/clang-version.sh | 18 +- > scripts/gcc-plugins/Makefile | 1 + > scripts/gcc-x86_32-has-stack-protector.sh | 7 +- > scripts/gcc-x86_64-has-stack-protector.sh | 5 - > scripts/kconfig/confdata.c | 33 +- > scripts/kconfig/kconf_id.c | 1 - > scripts/kconfig/lkc.h | 5 +- > scripts/kconfig/lkc_proto.h | 15 +- > scripts/kconfig/menu.c | 3 - > scripts/kconfig/preprocess.c | 572 +++++++++++++++++++++ > scripts/kconfig/symbol.c | 109 ---- > .../tests/no_write_if_dep_unmet/expected_config | 2 +- > .../kconfig/tests/preprocess/builtin_func/Kconfig | 27 + > .../tests/preprocess/builtin_func/__init__.py | 9 + > .../tests/preprocess/builtin_func/expected_stderr | 5 + > .../tests/preprocess/builtin_func/expected_stdout | 1 + > .../tests/preprocess/circular_expansion/Kconfig | 5 + > .../preprocess/circular_expansion/__init__.py | 11 + > .../preprocess/circular_expansion/expected_stderr | 1 + > scripts/kconfig/tests/preprocess/escape/Kconfig | 44 ++ > .../kconfig/tests/preprocess/escape/__init__.py | 8 + > .../tests/preprocess/escape/expected_stderr | 10 + > scripts/kconfig/tests/preprocess/variable/Kconfig | 53 ++ > .../kconfig/tests/preprocess/variable/__init__.py | 8 + > .../tests/preprocess/variable/expected_stderr | 9 + > scripts/kconfig/util.c | 33 +- > scripts/kconfig/zconf.l | 95 +++- > scripts/kconfig/zconf.y | 46 +- > 48 files changed, 1345 insertions(+), 567 deletions(-) > create mode 100644 Documentation/kbuild/kconfig-macro-language.txt > create mode 100644 scripts/Kconfig.include > create mode 100644 scripts/kconfig/preprocess.c > create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/Kconfig > create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/__init__.py > create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/expected_stderr > create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/expected_stdout > create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/Kconfig > create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/__init__.py > create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/expected_stderr > create mode 100644 scripts/kconfig/tests/preprocess/escape/Kconfig > create mode 100644 scripts/kconfig/tests/preprocess/escape/__init__.py > create mode 100644 scripts/kconfig/tests/preprocess/escape/expected_stderr > create mode 100644 scripts/kconfig/tests/preprocess/variable/Kconfig > create mode 100644 scripts/kconfig/tests/preprocess/variable/__init__.py > create mode 100644 scripts/kconfig/tests/preprocess/variable/expected_stderr > > -- > 2.7.4 > I pushed this series to git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kconfig-shell-v5 -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html