On Fri, Oct 4, 2019 at 3:28 PM Daniel T. Lee <danieltimlee@xxxxxxxxx> wrote: > > Currently, building the bpf samples isn't working. > Running make from the directory 'samples/bpf' will just shows following > result without compiling any samples. > > $ make > make -C ../../ /git/linux/samples/bpf/ BPF_SAMPLES_PATH=/git/linux/samples/bpf > make[1]: Entering directory '/git/linux' > CALL scripts/checksyscalls.sh > CALL scripts/atomic/check-atomics.sh > DESCEND objtool > make[1]: Leaving directory '/git/linux' > $ ls *kern.o > ls: cannot access '*kern.o': No such file or directory > > By using 'git bisect', found the problem is derived from below commit. > commit 394053f4a4b3 ("kbuild: make single targets work more correctly") > > > Currently, the single target build directly descends into the directory > > of the target. For example, > > > > $ make foo/bar/baz.o > > > > ... directly descends into foo/bar/. > > > > On the other hand, the normal build usually descends one directory at > > a time, i.e. descends into foo/, and then foo/bar/. > > > > This difference causes some problems. > > > > [...] > > > > This commit fixes those problems by making the single target build > > descend in the same way as the normal build does. > > Not familiar with kbuild, so I'm not sure why this led to build failure. > My humble guess is, samples/bpf/Makefile tries to run make from current > directory, 'sample/bpf', but somehow upper commit changed the way it works. > > samples/bpf/Makefile:232 > # Trick to allow make to be run from this directory > all: > $(MAKE) -C ../../ $(CURDIR)/ BPF_SAMPLES_PATH=$(CURDIR) > > I've tried to figure out the problem with 'make --trace', but not sure why > it's not working. Just a hunch with build directory. > > Any ideas to fix this problem? Yes, it's now a known problem. You need to run it as `make M=samples/bpf` from root directory, as well as have all the recent fixes both from bpf and bpf-next trees (:(, this will be a bit better once bpf is merged into bpf-next).
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