One nasty part of ATF is some of boolean macros are always defined
as 1 or 0, and the rest of them are only defined under certain
conditions.
For the former group, "#if FOO" or "#if !FOO" must be used because
"#ifdef FOO" is always true. (Options passed by $(call add_define,)
are the cases.)
For the latter, "#ifdef FOO" or "#ifndef FOO" should be used because
checking the value of an undefined macro is strange.
Here, IMAGE_BL* is handled by make_helpers/build_macro.mk like
follows:
$(eval IMAGE := IMAGE_BL$(call uppercase,$(3)))
$(OBJ): $(2)
@echo " CC $$<"
$$(Q)$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -D$(IMAGE) -c $$< -o $$@
This means, IMAGE_BL* is defined when building the corresponding
image, but *undefined* for the other images.
So, IMAGE_BL* belongs to the latter group where we should use #ifdef
or #ifndef.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>