On Thu, Nov 19, 2020 at 12:50 AM David Gow <davidgow@xxxxxxxxxx> wrote: > > 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> Seems sensible to me. I have no strong feeling as to whether we just turn this off on UML or whether we do the fix you proposed here though. Nevertheless, I would like to see *some* fix go in before v5.10 is released. Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>