On Wednesday 04 August 2021 17:43:41 Sean Anderson wrote: > On 8/2/21 3:21 PM, Simon Glass wrote: > > Hi Pali, > > > > On Mon, 2 Aug 2021 at 07:20, Pali Rohár <p...@kernel.org> wrote: > > > > > > Header file version.h does not use anything from timestamp.h. Including of > > > timestamp.h has side effect which cause recompiling object file at every > > > make run because timestamp.h changes at every run. > > > > > > So remove timestamp.h from version.h and include timestamp.h in files > > > which needs it. > > > > > > This change reduce recompilation time of final U-Boot binary when U-Boot > > > source files were not changed as less source files needs to be recompiled. > > > > > > Signed-off-by: Pali Rohár <p...@kernel.org> > > > --- > > > arch/arm/mach-rockchip/tpl.c | 4 ++++ > > > board/work-microwave/work_92105/work_92105_display.c | 1 + > > > cmd/version.c | 1 + > > > common/spl/spl.c | 4 ++++ > > > drivers/rtc/emul_rtc.c | 2 +- > > > include/version.h | 2 -- > > > 6 files changed, 11 insertions(+), 3 deletions(-) > > > > Reviewed-by: Simon Glass <s...@chromium.org> > > > > I assume we do actually want to regenerate the timestamp when U-Boot > > builds, even if nothing has changed. Is that right? > > I know this is the current behavior, but it would be nice if this was > not the case. If one is building U-Boot as part of a larger project, one > might want to have a makefile rule like > > u-boot/u-boot.bin: > $(MAKE) -C u-boot $(@F)
You are missing 'FORCE' prerequisite for u-boot/u-boot.bin target (but I understand what you mean; I'm using this stuff too). > but u-boot/u-boot.bin will always be remade even if no changes have been > done. This will cause make to remake all dependents of U-Boot as well > (which can be rather time-consuming). > > At the moment, I just use U-Boot as an order-only dependency and remake > it manually. But I would love it if U-Boot was only remade if > dependencies had actually changed, since this would make it easier to > integrate it with the rest of my build system. This behavior which you described is e.g. used by Linux kernel build system (also based on Makefile(s) and Kbuild as U-Boot). Maybe we can discuss if such change can or cannot be useful for U-Boot too. But to not make another confusion, it is not part and it is not related to this my patch series. So I would suggest to discuss about it in separate / new thread (fell free to CC me).