Re: [PATCH 00/10] bpf samples: Uses libbpf in tools/lib to do BPF operations

[Wangnan (F)]

On 2015/12/18 16:49, Daniel Wagner wrote:
> On 12/18/2015 04:04 AM, Wangnan (F) wrote:
> > On 2015/12/17 21:46, Daniel Wagner wrote:
> > > On 12/17/2015 11:09 AM, Wangnan (F) wrote:
> > > > On 2015/12/17 16:29, Daniel Wagner wrote:
> > > > > On 12/17/2015 08:03 AM, Daniel Wagner wrote:
> > > > > Patch number 2 didn't apply cleanly.
> > > > When you see this, could you please have a look at:
> > > >
> > > > /home/wagi/src/linux/samples/bpf/libbpf/feature/test-*.make.output
> > > >
> > > > ?
> > > test-libpython.c:1:20: fatal error: Python.h: No such file or directory
> > So it is the content in test-all.make.output ? Then it is
> > not a problem. It is only a fastpath which tries to check
> > all features by one test. On most platform it would fail.
> I see.
>
> > BPF related feature check is not in test-all. It is a potential
> > bug, but I don't think it causes your problem.
> >
> > Another problem is you didn't see this in the first failure:
> >
> > Auto-detecting system features:
> > ...                        libelf: [ on  ]
> > ...                           bpf: [ on  ]
> >
> > This only happen when you already have a FEATURE-DUMP.libbpf in that
> > directory and it is same as the feature check result.
> >
> > Could you please remove samples/bpf in your building tree and
> > try again? After you see the failure, what's the content of
> >
> > /home/wagi/src/linux/samples/bpf/libbpf/FEATURE-* ?
> I cleanup up my tree (rm samples/bpf/ and git checkout samples/bpf) and then
>
> $ make samples/bpf/
>    CHK     include/config/kernel.release
>    CHK     include/generated/uapi/linux/version.h
>    CHK     include/generated/utsrelease.h
>    CHK     include/generated/bounds.h
>    CHK     include/generated/timeconst.h
>    CHK     include/generated/asm-offsets.h
>    CALL    scripts/checksyscalls.sh
>    LD      samples/bpf/built-in.o
> make -C /home/wagi/src/linux/tools/lib/bpf O=/home/wagi/src/linux/samples/bpf/libbpf CFLAGS= LDFLAGS= V=1 /home/wagi/src/linux/samples/bpf/libbpf/libbpf.a
>
> Auto-detecting system features:
> ...                        libelf: [ OFF ]
> ...                           bpf: [ OFF ]

That's good. This is not a magic. I guess something in your top makefile
causes this feature check failure. I sent a patch on feature checker to you.
It will appear as [1] soon. Could you please apply it and try again?

This time you will see test-*.make.output and test-*.make.makeoutput.
test-*.make.output lists your PATH, PWD and the gcc command you use for
feature check. test-*.make.makeoutput is the output of 'make' itself. I 
think
from these information we can find the root cause easier.

Thank you.

[1] 
http://lkml.kernel.org/g/1450436211-170447-1-git-send-email-wangnan0@xxxxxxxxxx



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