On 22.01.2024 12:05, Anthony PERARD wrote: > On Mon, Jan 22, 2024 at 10:54:13AM +0000, Anthony PERARD wrote: >> On Mon, Jan 22, 2024 at 11:04:41AM +0100, Jan Beulich wrote: >>> On 19.01.2024 16:25, Anthony PERARD wrote: >>>> On Fri, Jan 19, 2024 at 09:43:30AM +0100, Michal Orzel wrote: >>>>> Is my understanding correct that by switching from extra-y to targets we >>>>> are preventing these objects to >>>>> appear in non-init-objects (and thus having COV_FLAGS appended) while >>>>> retaining the proper if_changed behavior? >>>>> >>>>> According to docs/misc/xen-makefiles/makefiles.rst: >>>>> Any target that utilises if_changed must be listed in $(targets), >>>>> otherwise the command line check will fail, and the target will >>>>> always be built. >>>> >>>> Indeed, and $(extra-y) is added to $(targets) via >>>> $(targets-for-builtin). >>>> >>>> While switching from $(extra-y) to $(targets) prevents the objects from >>>> been added to $(non-init-objets), it doesn't matter because "libelf.o" >>>> is in that variable, so $(COV_FLAGS) is added to $(_c_flags) and its >>>> value is used in all the prerequisites of "libelf.o" which includes >>>> "libelf-temp.o" and for example "libelf-dominfo.o". So the only thing >>>> preventing $(COV_FLAGS) from been added when building "libelf-tools.o" >>>> for example is that we set `COV_FLAGS:=` for "libelf.o". >>> >>> Yet doesn't that (again) mean things should actually work as-is, [...] >> >> No, because I've explain how it should work, in the hypothetical world >> where we have `targets += libelf-temp.o $(libelf-objs)`. > > The problem is that there's currently two "paths" to build libelf-temp.o > (and even three I think for libelf-tools.o libelf-loader.o > libelf-dominfo.o): > > Simplified makefile: > > obj-y := libelf.o > extra-y := libelf-temp.o > COV_FLAGS := -fcoverage > > __build: $(extra-y) built_in.o
Oh, okay - this is the piece I was missing. Thanks for the explanation. Jan > built_in.o: $(obj-y) > libelf.o: COV_FLAGS := > libelf.o: libelf-temp.o > > So, make can build "libelf-temp.o" as prerequisite of "__build" the > default target, or as prerequisite of "libelf.o". > In the first case, COV_FLAGS would have all the flags, and in the second > case, COV_FLAGS would be reset, but that second case is too late as make > is more likely to have already built libelf-temp.o with all the flags. > > Cheers, >
