On 17/10/2023 12.44, Richard Marko wrote:
If we try to build using external dtc using
make DTC=dtc
we get a confusing error like
make[2]: *** No rule to make target 'arch/x86/dts/bayleybay.dtb', needed by 'dtbs'. Stop.
Workaround is to use
make DTC=$( which dtc )
which gives make a full path, so the dependency is satisfied.
This was introduced by commit d50af66 kbuild: add dtc as dependency on .dtb files
and we extend it so it calls which automatically (similar to scripts/dtc-version.sh)
Let's please not deviate from linux Kbuild unless we absolutely have to. In this case, passing an absolute path works just fine, and is AFAICT the only documented way to pass DTC. E.g. doc/build/gcc.rst has
DTC=/usr/bin/dtc make
as example.
[And if we do this, then at the very least this should also be done for the .dtbo rule and wherever else $(DTC) is used. But I'm really not a fan of calling out to $(shell which ...) in the rule itself. Perhaps if it was done just once, near DTC/DTC_IN_TREE, something like (not real make syntax I think)
ifneq ($(DTC), $(DTC_IN_TREE)) DTC := $(shell which $(DTC)) endif
But I don't think we should be doing this at all.]
Rasmus