[U-Boot] [RFC/PATCH] Makefile: allow boards to check file size limits

[Mike Frysinger]

Boards often have a reserved size limit on the flash where they're stored.
Sometimes during upgrades or config changes, those limits are exceeded,
but no one notices until they try to upgrade and the limit screws things
up.  Either not enough of U-Boot is written to flash (and so the reboot
fails), or too much is written (and so things after it get clobbered).

So allow boards to declare a size limit (in bytes) and have the build
system check it while building.

Signed-off-by: Mike Frysinger <vapier at gentoo.org>
---
 Makefile |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/Makefile b/Makefile
index de4ceb9..ca12d78 100644
--- a/Makefile
+++ b/Makefile
@@ -304,6 +304,21 @@ __LIBS := $(subst $(obj),,$(LIBS)) $(subst $(obj),,$(LIBBOARD))
 #########################################################################
 #########################################################################
 
+ifneq ($(CONFIG_BOARD_SIZE_LIMIT),)
+BOARD_SIZE_CHECK = \
+	@actual=`wc -c $@ | awk '{print $$1}'`; \
+	limit=$(CONFIG_BOARD_SIZE_LIMIT); \
+	if test $$actual -gt $$limit; then \
+		echo "$@ exceeds file size limit:"; \
+		echo "  limit:  $$limit bytes"; \
+		echo "  actual: $$actual bytes"; \
+		echo "  excess: $$((actual - limit)) bytes"; \
+		exit 1; \
+	fi
+else
+BOARD_SIZE_CHECK =
+endif
+
 # Always append ALL so that arch config.mk's can add custom ones
 ALL += $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map $(U_BOOT_NAND) $(U_BOOT_ONENAND)
 
@@ -317,10 +332,12 @@ $(obj)u-boot.srec:	$(obj)u-boot
 
 $(obj)u-boot.bin:	$(obj)u-boot
 		$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@
+		$(BOARD_SIZE_CHECK)
 
 $(obj)u-boot.ldr:	$(obj)u-boot
 		$(CREATE_LDR_ENV)
 		$(LDR) -T $(CONFIG_BFIN_CPU) -c $@ $< $(LDR_FLAGS)
+		$(BOARD_SIZE_CHECK)
 
 $(obj)u-boot.ldr.hex:	$(obj)u-boot.ldr
 		$(OBJCOPY) ${OBJCFLAGS} -O ihex $< $@ -I binary
-- 
1.7.3.1