On Wed, Feb 27, 2019 at 11:17 AM Masahiro Yamada yamada.masahiro@socionext.com wrote:
On Wed, Feb 27, 2019 at 4:21 AM Stephen Warren swarren@wwwdotorg.org wrote:
From: Stephen Warren swarren@nvidia.com
Without this, the arch-dtbs target only gets evaluated when building U-Boot the first time, not when re-building (incrementally building) U-Boot. Thus incremental builds ignore changes to DTB files.
Really?
I tested "touch DT, then incremental build", and it correctly re-compiled device tree.
I attached the log of the following build sequence:
[1] make jetson-tk1_defconfig [2] make CROSS_COMPILE=arm-linux-gnueabihf- [3] touch arch/arm/dts/tegra124-jetson-tk1.dts [4] make CROSS_COMPILE=arm-linux-gnueabihf-
Hmm, OK. Understood.
The jetson DT was recompiled, but the other tegra DT files were not.
So, I am fine with this patch, but this Makefile is problematic already.
Looking into dts/Makefile, I noticed there are two ways to descend into arch/*/dts.
$(DTB): $(dtb_depends) ifeq ($(EXT_DTB),) $(Q)$(MAKE) $(build)=$(ARCH_PATH) $@ <----- [1] endif $(Q)test -e $@ || ( \ echo >&2; \ echo >&2 "Device Tree Source is not correctly specified."; \ echo >&2 "Please define 'CONFIG_DEFAULT_DEVICE_TREE'"; \ echo >&2 "or build with 'DEVICE_TREE=<device_tree>' argument"; \ echo >&2; \ /bin/false)
arch-dtbs: $(Q)$(MAKE) $(build)=$(ARCH_PATH) dtbs <----- [2]
[1] and [2] would cause a race in parallel building and might produce an invalid DTB.
I do not understand commit 27cb7300ffda7a3f1581f0f5a2d3bfe59b97ad67