[PATCH 2/5] kbuild: images: don't check for missing FW if file didn't change

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The information about the missing firmware is contained in an ELF
section and the ELF file is dependency to the $(obj)/%.pblb: $(obj)/%.pbl
rule.

We can thus don't need to rerun the missing firmware check if the
input file hasn't been changed since the last time.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 images/Makefile      | 3 +--
 scripts/Makefile.lib | 6 ++++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/images/Makefile b/images/Makefile
index 80ea582728a5..f781ecb59ccb 100644
--- a/images/Makefile
+++ b/images/Makefile
@@ -76,8 +76,7 @@ $(obj)/%.elf: $(pbl-lds) $(BAREBOX_PBL_OBJS) $(obj)/piggy.o $(obj)/sha_sum.o FOR
 
 $(obj)/%.pblb: $(obj)/%.pbl FORCE
 	$(call if_changed,objcopy_bin,$(*F))
-	$(Q)$(OBJCOPY) -O binary --only-section=.missing_fw $< $@.missing-firmware
-	$(Q)[ -s $@.missing-firmware ] || rm -f $@.missing-firmware
+	$(call if_changed,check_missing_fw,$@,$<)
 	$(call if_changed,check_file_size,$@,$(CONFIG_BAREBOX_MAX_IMAGE_SIZE))
 
 #
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index b698161f43f6..e2d0168550f8 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -533,6 +533,12 @@ quiet_cmd_check_file_size = CHKFILESIZE $2
 		exit 1 ;						\
 	fi
 
+# Check for missing firmware
+quiet_cmd_check_missing_fw = # no message as we collect info for later
+      cmd_check_missing_fw = set -e;						    \
+	$(OBJCOPY) -O binary --only-section=.missing_fw	$3 $2.missing-firmware;	    \
+	[ -s $2.missing-firmware ] || rm -f $2.missing-firmware
+
 quiet_cmd_imximage__S_dcd= DCD_S   $@
 cmd_imximage_S_dcd=						\
 (								\
-- 
2.39.5