[PATCH] libbpf: Remove arch-specific include path in Makefile

From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@redhat.com>,
	Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
Subject: [PATCH] libbpf: Remove arch-specific include path in Makefile
Date: Wed,  2 Sep 2020 14:12:46 +0530	[thread overview]
Message-ID: <20200902084246.1513055-1-naveen.n.rao@linux.vnet.ibm.com> (raw)

Ubuntu mainline builds for ppc64le are failing with the below error (*):
    CALL    /home/kernel/COD/linux/scripts/atomic/check-atomics.sh
    DESCEND  bpf/resolve_btfids

  Auto-detecting system features:
  ...                        libelf: [ [32mon[m  ]
  ...                          zlib: [ [32mon[m  ]
  ...                           bpf: [ [31mOFF[m ]

  BPF API too old
  make[6]: *** [Makefile:295: bpfdep] Error 1
  make[5]: *** [Makefile:54: /home/kernel/COD/linux/debian/build/build-generic/tools/bpf/resolve_btfids//libbpf.a] Error 2
  make[4]: *** [Makefile:71: bpf/resolve_btfids] Error 2
  make[3]: *** [/home/kernel/COD/linux/Makefile:1890: tools/bpf/resolve_btfids] Error 2
  make[2]: *** [/home/kernel/COD/linux/Makefile:335: __build_one_by_one] Error 2
  make[2]: Leaving directory '/home/kernel/COD/linux/debian/build/build-generic'
  make[1]: *** [Makefile:185: __sub-make] Error 2
  make[1]: Leaving directory '/home/kernel/COD/linux'

resolve_btfids needs to be build as a host binary and it needs libbpf.
However, libbpf Makefile hardcodes an include path utilizing $(ARCH).
This results in mixing of cross-architecture headers resulting in a
build failure.

The specific header include path doesn't seem necessary for a libbpf
build. Hence, remove the same.

(*) https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.9-rc3/ppc64el/log

Reported-by: Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
This is a simpler fix that seems to work and I saw the proper headers 
from within tools/ being included in both cross-architecture builds as 
well as a native ppc64le build. I am not sure if there is a better way 
to ask kbuild to build resolve_btfids/libbpf for the host architecture, 
and if that will set $(ARCH) appropriately.

- Naveen


 tools/lib/bpf/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index adbe994610f2..fccc4dcda4b6 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -62,7 +62,7 @@ FEATURE_USER = .libbpf
 FEATURE_TESTS = libelf zlib bpf
 FEATURE_DISPLAY = libelf zlib bpf
 
-INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
+INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/include/uapi
 FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)
 
 check_feat := 1

base-commit: 0697fecf7ecd8abf70d0f46e6a352818e984cc9f
-- 
2.25.4

