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/arch/ppc/Makefile b/arch/ppc/Makefile
index 98e940b..9fbdf54 100644
--- a/arch/ppc/Makefile
+++ b/arch/ppc/Makefile
@@ -82,7 +82,7 @@
BOOT_TARGETS = zImage zImage.initrd znetboot znetboot.initrd vmlinux.sm
-.PHONY: $(BOOT_TARGETS)
+PHONY += $(BOOT_TARGETS)
all: uImage zImage
