kbuild: change kbuild to not rely on incorrect GNU make behavior
The kbuild system takes advantage of an incorrect behavior in GNU make.
Once this behavior is fixed, all files in the kernel rebuild every time,
even if nothing has changed. This patch ensures kbuild works with both
the incorrect and correct behaviors of GNU make.
For more details on the incorrect behavior, see:
http://lists.gnu.org/archive/html/bug-make/2006-03/msg00003.html
Changes in this patch:
- Keep all targets that are to be marked .PHONY in a variable, PHONY.
- Add .PHONY: $(PHONY) to mark them properly.
- Remove any $(PHONY) files from the $? list when determining whether
targets are up-to-date or not.
Signed-off-by: Paul Smith <psmith@gnu.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 8974ea5..cff3349 100644
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -4,7 +4,7 @@
src := $(obj)
-.PHONY: __clean
+PHONY := __clean
__clean:
# Shorthand for $(Q)$(MAKE) scripts/Makefile.clean obj=dir
@@ -87,10 +87,16 @@
# Descending
# ---------------------------------------------------------------------------
-.PHONY: $(subdir-ymn)
+PHONY += $(subdir-ymn)
$(subdir-ymn):
$(Q)$(MAKE) $(clean)=$@
# If quiet is set, only print short version of command
cmd = @$(if $($(quiet)cmd_$(1)),echo ' $($(quiet)cmd_$(1))' &&) $(cmd_$(1))
+
+
+# Declare the contents of the .PHONY variable as phony. We keep that
+# information in a variable se we can use it in if_changed and friends.
+
+.PHONY: $(PHONY)