On Mon, Jan 31, 2022 at 02:10:30PM +0000, Jean-Philippe Brucker wrote: > Hi Nathan, > > On Fri, Jan 28, 2022 at 06:10:24PM -0700, Nathan Chancellor wrote: > > > diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include > > > index 071312f5eb92..b0be5f40a3f1 100644 > > > --- a/tools/scripts/Makefile.include > > > +++ b/tools/scripts/Makefile.include > > > @@ -87,7 +87,18 @@ LLVM_STRIP ?= llvm-strip > > > > > > ifeq ($(CC_NO_CLANG), 1) > > > EXTRA_WARNINGS += -Wstrict-aliasing=3 > > > -endif > > > + > > > +else ifneq ($(CROSS_COMPILE),) > > > +CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > > +GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc)) > > > > Apologies for noticing this so late, I only ran into this recently. > > > > This line causes a warning when running 'make clean' when > > '$(CROSS_COMPILE)gcc' does not exist in PATH. For example: > > > > $ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu- LLVM=1 LLVM_IAS=0 clean > > which: no powerpc-linux-gnu-gcc in ($PATH) > > > > I only have powerpc-linux-gnu binutils in my PATH, not GCC, as I am only > > working with clang. > > > > This happens because of the 'resolve_btfids_clean target', which always > > runs when running the 'clean' target on an in-tree build (since > > $(objtree) = $(srctree)). > > > > I tried looking into the best way to fix this but I am not at all > > familiar with the tools/ build system; would you mind taking a look? > > I see some machinery at the top of tools/bpf/Makefile for avoiding > > running some commands under certain commands but I am unsure how to > > shuffle that around to make everything work. > > I think it's simpler than that, we should just suppress the errors from > 'which'. It's fine that $(CROSS_COMPILE)gcc doesn't exist and > $(GCC_TOOLCHAIN_DIR) is empty, but 'which' should keep quiet about it. Ha, that's what I get for looking into something at the very end of a long work week because that is a great and simple solution I probably would not have seen :) > I did test this patch with cross-build and no gcc, but Debian's 'which' is > quiet by default so I missed the error. I'll send a fix shortly. Ah, that is an interesting observation. TIL that Debian rolls their own which [1], versus most other distros, which use GNU which [2]. I will keep an eye out for your patch so I can review it. [1]: https://salsa.debian.org/debian/debianutils/-/blob/de14223e5bffe15e374a441302c528ffc1cbed57/which [2]: https://savannah.gnu.org/projects/which/ Cheers, Nathan
