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 pali@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 pali@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 sjg@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).