In my view, most of headers can be self-contained. So, it would be tedious to add every header to header-test-y explicitly. We usually end up with "all headers with some exceptions". There are two types in exceptions: [1] headers that are never compiled as standalone units For examples, include/linux/compiler-gcc.h is not intended to be included directly. We should always exclude such ones. [2] headers that are conditionally compiled as standalone units Some headers can be compiled only for particular architectures. For example, include/linux/arm-cci.h can be compiled only for arm/arm64 because it requires <asm/arm-cci.h> to exist. Clang can compile include/soc/nps/mtm.h only for arc because it contains an arch-specific register in inline assembler. For [2], we can write Makefile like this: header-test-$(CONFIG_ARM) += linux/arm-cci.h The new syntax header-test-pattern-y will be useful to specify "the rest". The typical usage is like this: header-test-pattern-y += */*.h This adds all the headers in sub-directories to the test coverage, but headers added to header-test- are excluded. In this regards, header-test-pattern-y behaves like a weaker variant of header-test-y. Caveat: The patterns in header-test-pattern-y are prefixed with $(srctree)/$(src)/ but not $(objtree)/$(obj)/. Stale generated patterns are often left over. For example, you will have ones when you traverse the git history for 'git bisect' without cleaning. If a wildcard is used for generated headers, it may match to stale headers. If you really want to compile-test generated headers, I recommend to add them to header-test-y explicitly. One pitfall is $(srctree)/$(src)/ and $(objtree)/$(obj)/ point to the same directory for in-tree building. So, header-test-pattern-y should be used with care. It can potentially match to generated headers, which may be stale and fail to compile. Caveat2: You could use wildcard for header-test-. For example, header-test- += asm-generic/% ... will exclude headers in asm-generic directory. Unfortunately, the wildcard character is '%' instead of '*' because this is evaluated by $(filter-out ...) whereas header-test-pattern-y is evaluated by $(wildcard ...). This is a kludge, but seems useful in some places... Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- Changes in v2: - New patch Documentation/kbuild/makefiles.txt | 10 ++++++++++ scripts/Makefile.lib | 10 ++++++++++ 2 files changed, 20 insertions(+) diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 5080fec34609..b817e6cefb77 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -1025,6 +1025,16 @@ When kbuild executes, the following steps are followed (roughly): i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled, this builds them as part of extra-y. + header-test-pattern-y + + This works as a weaker version of header-test-y, and accepts wildcard + patterns. The typical usage is: + + header-test-pattern-y += *.h + + This specifies all the files that matches to '*.h' in the current + directory, but the files in 'header-test-' are excluded. + --- 6.7 Commands useful for building a boot image Kbuild provides a few macros that are useful when building a diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 55ae1ec65342..54444933bbab 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -67,6 +67,16 @@ extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-)) endif # Test self-contained headers + +# Wildcard searches in $(srctree)/$(src)/, but not in $(objtree)/$(obj)/. +# Stale generated headers are often left over, so wildcard matching should +# be avoided. Please notice $(srctree)/$(src)/ and $(objtree)/$(obj) point +# to the same location for in-tree building. +header-test-y += $(filter-out $(header-test-), \ + $(patsubst $(srctree)/$(src)/%, %, \ + $(wildcard $(addprefix $(srctree)/$(src)/, \ + $(header-test-pattern-y))))) + extra-$(CONFIG_HEADER_TEST) += $(addsuffix .s, $(header-test-y)) # Add subdir path -- 2.17.1
