On 2017-04-03 09:42, Masahiro Yamada wrote: > Each Makefile knows it wants to see > additional headers in the source tree, or objtree. > > I am guessing the right approach in a long run is, > we require -I to specify $(srctree) or $(objtree) explicitly. > > ccflags-y := -I$(srctree)/foo/bar/baz > > or > > ccflags-y := -I$(objtree)/foo/bar/baz > > > (For the latter, we can omit $(objtree)/ as it is ./) > > > Then, delete $(call flags,_c_flags) after the conversion. Agreed. The addtree function is more of a hack to make things just work with O=, but AFAIK there is no clean way to implement VPATH for -I arguments. So it's sensible to get rid of the hack. It looks like it's going to be lot of work though: $ git grep -e '-I' -- '*Makefile*' | wc -l 732 $ git grep -e '-I *\$(\(src\|obj\)tree)' -- '*Makefile*' | wc -l 166 Michal