On Thu, 27 Jun 2019, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > 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> Awesome! This will let us get rid of our local $(wildcard) hacks. Tested-by: Jani Nikula <jani.nikula@xxxxxxxxx> > --- > > Changes in v2: > - New patch > > Documentation/kbuild/makefiles.txt | 10 ++++++++++ > scripts/Makefile.lib | 10 ++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt > index 5080fec34609..b817e6cefb77 100644 > --- a/Documentation/kbuild/makefiles.txt > +++ b/Documentation/kbuild/makefiles.txt > @@ -1025,6 +1025,16 @@ When kbuild executes, the following steps are followed (roughly): > i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled, > this builds them as part of extra-y. > > + header-test-pattern-y > + > + This works as a weaker version of header-test-y, and accepts wildcard > + patterns. The typical usage is: > + > + header-test-pattern-y += *.h > + > + This specifies all the files that matches to '*.h' in the current > + directory, but the files in 'header-test-' are excluded. > + > --- 6.7 Commands useful for building a boot image > > Kbuild provides a few macros that are useful when building a > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 55ae1ec65342..54444933bbab 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -67,6 +67,16 @@ extra-$(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 -- Jani Nikula, Intel Open Source Graphics Center
