On Sat, May 07, 2016 at 03:48:26PM +0900, Masahiro Yamada wrote: > Currently, arg-check is implemented as follows: > > arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \ > $(filter-out $(cmd_$@), $(cmd_$(1))) ) > > This does not care about the order of arguments that appear in > $(cmd_$(1)) and $(cmd_$@). So, if_changed and friends never rebuild > the target if only the argument order is changed. This is a problem > when the link order is changed. > > Apparently, > > obj-y += foo.o > obj-y += bar.o > > and > > obj-y += bar.o > obj-y += foo.o > > should be distinguished because the link order determines the probe > order of drivers. So, built-in.o should be rebuilt when the order > of objects is changed. > > This commit fixes arg-check to compare the old/current commands > including the argument order. > > Of course, this change has a side effect; Kbuild will react to the > change of compile option order. For example, "-DFOO -DBAR" and > "-DBAR -DFOO" should give no difference to the build result, but > false positive should be better than false negative.
Agreed. Applied to kbuild.git#kbuild now. Michal
