Since now, the unnecessary rebuild of ITB has been fixed. Another problem to be taken care of is, missed rebuild of ITB. For example, board-boston.its.S includes boston.dtb by the /incbin/ directive. If boston.dtb is updated, vmlinux.*.dtb must be rebuilt. Currently, the dependency between ITB and contained DTB files is not described anywhere. Previously, this problem was hidden since vmlinux.*.itb was always rebuilt even if nothing is updated. By fixing the spurious rebuild, this is a real problem now. Use the same strategy for automatic generation of the header file dependency. DTC works as a backend of mkimage, and DTC supports -d option. It outputs the dependencies, including binary files pulled by the /incbin/ directive. The implementation is simpler than cmd_dtc in scripts/Makefile.lib since we do not need CPP here. Just pass -d $(depfile) to DTC, and let the resulted $(depfile) processed by fixdep. It might be unclear why "$(obj)/dts/%.dtb: ;" is needed. With this commit, *.cmd files will contain dependency on DTB files. In the next invocation of build, the *.cmd files will be included, then Make will try to find a rule to update *.dtb files. Unfortunately, it is found in scripts/Makefile.lib. The build rule of $(obj)/%.dtb is invoked by if_changed_dep, so it needs to include *.cmd files of DTB, but they are not included because we are in arch/mips/boot, but those *.cmd files reside in arch/mips/boot/dts/*/. Cancel the pattern rule in scripts/Makefile.lib to suppress unneeded rebuilding of DTB. Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- arch/mips/boot/Makefile | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/mips/boot/Makefile b/arch/mips/boot/Makefile index d102d53..f8dce5b 100644 --- a/arch/mips/boot/Makefile +++ b/arch/mips/boot/Makefile @@ -163,11 +163,18 @@ quiet_cmd_itb-image = ITB $@ $(CONFIG_SHELL) $(MKIMAGE) \ -D "-I dts -O dtb -p 500 \ --include $(objtree)/arch/mips \ - --warning no-unit_address_vs_reg" \ + --warning no-unit_address_vs_reg \ + -d $(depfile)" \ -f $(2) $@ $(obj)/vmlinux.itb: $(obj)/vmlinux.its $(obj)/vmlinux.bin FORCE - $(call if_changed,itb-image,$<) + $(call if_changed_dep,itb-image,$<) $(obj)/vmlinux.%.itb: $(obj)/vmlinux.%.its $(obj)/vmlinux.bin.% FORCE - $(call if_changed,itb-image,$<) + $(call if_changed_dep,itb-image,$<) + +# The -d option of DTC outputs dependencies of binaries included by the +# /incbin/ directive. When .*.cmd files are included, Kbuild tries to +# update *.dtb because it sees a pattern rule defined in scripts/Makefile.lib. +# The rule must be cancelled by a more specific rule. +$(obj)/dts/%.dtb: ; -- 2.7.4
