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/de14223e5bffe15e374a44130... [2]: https://savannah.gnu.org/projects/which/
Cheers, Nathan