From: David Gow <davidgow@google.com>
To: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: David Gow <davidgow@google.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org,
Brendan Higgins <brendanhiggins@google.com>
Subject: [RFC PATCH] bpf: preload: Fix build error when O= is set
Date: Thu, 19 Nov 2020 00:50:23 -0800 [thread overview]
Message-ID: <20201119085022.3606135-1-davidgow@google.com> (raw)
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@google.com>
---
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
next reply other threads:[~2020-11-19 8:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 8:50 David Gow [this message]
2020-11-19 21:14 ` [RFC PATCH] bpf: preload: Fix build error when O= is set Brendan Higgins
2020-11-21 7:37 ` Andrii Nakryiko
2020-11-21 9:48 ` David Gow
2020-12-16 14:53 ` Quentin Monnet
2020-12-17 9:05 ` David Gow
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