If BPF_PRELOAD is enabled, and an out-of-tree build is requested with make O=<path>, compilation seems to fail with: tools/scripts/Makefile.include:4: *** O=.kunit does not exist. Stop. make[4]: *** [../kernel/bpf/preload/Makefile:8: kernel/bpf/preload/libbpf.a] Error 2 make[3]: *** [../scripts/Makefile.build:500: kernel/bpf/preload] Error 2 make[2]: *** [../scripts/Makefile.build:500: kernel/bpf] Error 2 make[2]: *** Waiting for unfinished jobs.... make[1]: *** [.../Makefile:1799: kernel] Error 2 make[1]: *** Waiting for unfinished jobs.... make: *** [Makefile:185: __sub-make] Error 2 By the looks of things, this is because the (relative path) O= passed on the command line is being passed to the libbpf Makefile, which then can't find the directory. Given OUTPUT= is being passed anyway, we can work around this by explicitly setting an empty O=, which will be ignored in favour of OUTPUT= in tools/scripts/Makefile.include. Signed-off-by: David Gow <davidgow@xxxxxxxxxx> --- Hi all, I'm not 100% sure this is the correct fix here -- it seems to work for me, and makes some sense, but let me know if there's a better way. One other thing worth noting is that I've been hitting this with make allyesconfig on ARCH=um, but there's a comment in the Kconfig suggesting that, because BPF_PRELOAD depends on !COMPILE_TEST, that maybe it shouldn't be being built at all. I figured that it was worth trying to fix this anyway. Cheers, -- David kernel/bpf/preload/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile index 23ee310b6eb4..39848d296097 100644 --- a/kernel/bpf/preload/Makefile +++ b/kernel/bpf/preload/Makefile @@ -5,7 +5,7 @@ LIBBPF_A = $(obj)/libbpf.a LIBBPF_OUT = $(abspath $(obj)) $(LIBBPF_A): - $(Q)$(MAKE) -C $(LIBBPF_SRCS) OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a + $(Q)$(MAKE) -C $(LIBBPF_SRCS) O= OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ -I $(srctree)/tools/lib/ -Wno-unused-result -- 2.29.2.454.gaff20da3a2-goog
