acrn-kernel/arch/um/scripts/Makefile.rules

# ===========================================================================
# arch/um: Generic definitions
# ===========================================================================

USER_SINGLE_OBJS := \
	$(foreach f,$(patsubst %.o,%,$(obj-y) $(obj-m)),$($(f)-objs))
USER_OBJS += $(filter %_user.o,$(obj-y) $(obj-m)  $(USER_SINGLE_OBJS))
USER_OBJS := $(foreach file,$(USER_OBJS),$(obj)/$(file))

$(USER_OBJS) $(USER_OBJS:.o=.i) $(USER_OBJS:.o=.s) $(USER_OBJS:.o=.lst): \
	c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) $(CFLAGS_$(notdir $@))
$(USER_OBJS): cmd_checksrc =
$(USER_OBJS): quiet_cmd_checksrc =
$(USER_OBJS): cmd_force_checksrc =
$(USER_OBJS): quiet_cmd_force_checksrc =


# The stubs and unmap.o can't try to call mcount or update basic block data
define unprofile
	$(patsubst -pg,,$(patsubst -fprofile-arcs -ftest-coverage,,$(1)))
endef


# cmd_make_link checks to see if the $(foo-dir) variable starts with a /.  If
# so, it's considered to be a path relative to $(srcdir) rather than
# $(srcdir)/arch/$(SUBARCH).  This is because x86_64 wants to get ldt.c from
# arch/um/sys-i386 rather than arch/i386 like the other borrowed files.  So,
# it sets $(ldt.c-dir) to /arch/um/sys-i386.
quiet_cmd_make_link = SYMLINK $@
cmd_make_link       = rm -f $@; ln -sf $(srctree)$(if $(filter-out /%,$($(notdir $@)-dir)),/arch/$(SUBARCH))/$($(notdir $@)-dir)/$(notdir $@) $@

# this needs to be before the foreach, because targets does not accept
# complete paths like $(obj)/$(f). To make sure this works, use a := assignment
# or we will get $(obj)/$(f) in the "targets" value.
# Also, this forces you to use the := syntax when assigning to targets.
# Otherwise the line below will cause an infinite loop (if you don't know why,
# just do it).

targets := $(targets) $(SYMLINKS)

SYMLINKS := $(foreach f,$(SYMLINKS),$(obj)/$(f))

$(SYMLINKS): FORCE
	$(call if_changed,make_link)