On Wed, Aug 04, 2021 at 05:43:41PM -0400, 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)
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.
Note that with this series applied, if you made use of SOURCE_DATE_EPOCH, nothing would be rebuilt. That may or may not make sense however, in your case. This series does get us closer to being able to do what the linux kernel does as there's now just one place rather than a bunch of places that are rebuilt.