[PATCH v4 00/31] kconfig: move compiler capability tests to Kconfig

Masahiro Yamada
2018-05-17T06:18:51Z

[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 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]

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: 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', and 'error' built-in functions
kconfig: add 'if' built-in function
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
arm64: move GCC version check for ARCH_SUPPORTS_INT128 to Kconfig

Documentation/kbuild/kconfig-language.txt | 8 -
Documentation/kbuild/kconfig-macro-language.txt | 252 ++++++++
Kconfig | 10 +-
MAINTAINERS | 3 +-
Makefile | 105 +---
arch/Kconfig | 49 +-
arch/arm64/Kconfig | 1 +
arch/arm64/Makefile | 6 -
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 | 27 +
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 | 4 -
scripts/kconfig/lkc_proto.h | 15 +-
scripts/kconfig/menu.c | 3 -
scripts/kconfig/preprocess.c | 651 +++++++++++++++++++++
scripts/kconfig/symbol.c | 109 ----
.../kconfig/tests/preprocess/builtin_func/Kconfig | 29 +
.../tests/preprocess/builtin_func/__init__.py | 8 +
.../tests/preprocess/builtin_func/expected_stderr | 7 +
.../tests/preprocess/builtin_func/expected_stdout | 1 +
.../tests/preprocess/circular_expansion/Kconfig | 3 +
.../preprocess/circular_expansion/__init__.py | 10 +
.../preprocess/circular_expansion/expected_stderr | 1 +
scripts/kconfig/tests/preprocess/escape/Kconfig | 21 +
.../kconfig/tests/preprocess/escape/__init__.py | 7 +
.../tests/preprocess/escape/expected_stderr | 5 +
scripts/kconfig/tests/preprocess/variable/Kconfig | 48 ++
.../kconfig/tests/preprocess/variable/__init__.py | 7 +
.../tests/preprocess/variable/expected_stderr | 9 +
scripts/kconfig/util.c | 22 +-
scripts/kconfig/zconf.l | 95 ++-
scripts/kconfig/zconf.y | 46 +-
49 files changed, 1366 insertions(+), 572 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

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2.7.4