On 11/12/19 1:50 PM, Masahiro Yamada wrote:
On Tue, Nov 12, 2019 at 9:31 PM Will Deacon <will@xxxxxxxxxx> wrote:
[+lkml, Masahiro, Alexei and Daniel]
On Tue, Nov 12, 2019 at 04:56:39PM +0800, Xiao Yang wrote:
With your patch[1], I alway get the following error when building
tools/bpf:
In case people want to reproduce this, my branch is here:
https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=lto
----------------------------------------------------------------------------------
make -C tools/bpf/
make: Entering directory
'/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf'
Auto-detecting system features:
... libbfd: [ on ]
... disassembler-four-args: [ OFF ]
CC bpf_jit_disasm.o
CC bpf_dbg.o
In file included from
/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/uapi/linux/filter.h:9:0,
from
/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf/bpf_dbg.c:41:
/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/linux/compiler.h:247:24:
fatal error: asm/rwonce.h: No such file or directory
#include <asm/rwonce.h>
^
compilation terminated.
Makefile:61: recipe for target 'bpf_dbg.o' failed
make: *** [bpf_dbg.o] Error 1
make: *** Waiting for unfinished jobs....
make: Leaving directory
----------------------------------------------------------------------------------
[1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/commit/?h=lto&id=642a312d47ceb54603630d9d04f5052f3b46d9a3
It seems that include/linux/compiler.h cannot find the asm/rwonce.h because
tools/bpf/Makefile doesn't include arch/*/include/generated/asm/rwonce.h.
The problem with referring to the generated files is that they don't exist
unless you've configured the main source directory. The real problem here
seems to be that tools/bpf/ refers directly to header files in the kernel
sources without any understanding of kbuild, and therefore mandatory-y
headers simply don't exist when it goes looking for them.
Hmm, I am puzzled why that is. :/ I think there are two options, i) remove it
from CFLAGS like below (at least this doesn't let the build fail in my case
but requires linux headers to be installed) or ii) add a copy of filter.h to
tools/include/uapi/linux/filter.h so the few tools can just reuse it. We do have
bpf_common.h and bpf.h there already.
diff --git a/tools/bpf/Makefile b/tools/bpf/Makefile
index 5d1995fd369c..08dfd289174c 100644
--- a/tools/bpf/Makefile
+++ b/tools/bpf/Makefile
@@ -10,7 +10,6 @@ MAKE = make
INSTALL ?= install
CFLAGS += -Wall -O2
-CFLAGS += -D__EXPORTED_HEADERS__ -I$(srctree)/include/uapi -I$(srctree)/include
# This will work when bpf is built in tools env. where srctree
# isn't set and when invoked from selftests build, where srctree
Thanks,
Daniel
