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

[Wangnan (F)]

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.
> > Because I have another patch in my local tree which also modifis bpf
> > Makefile:
> >
> > http://lkml.kernel.org/g/1450316632-152513-1-git-send-email-wangnan0@xxxxxxxxxx
> >
> > sorry.
> Ah, that explains it this problem.
>
> > > After fixing this manually
> > > I was able to continue to the build step:
> > >
> > > $ 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
> > > 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
> > > No libelf found
> > > Makefile:203: recipe for target 'elfdep' failed
> > > make[2]: *** [elfdep] Error 255
> > > samples/bpf/Makefile:10: recipe for target
> > > 'samples/bpf/libbpf/libbpf.a' failed
> > > make[1]: *** [samples/bpf/libbpf/libbpf.a] Error 2
> > > Makefile:1550: recipe for target 'samples/bpf/' failed
> > > make: *** [samples/bpf/] Error 2
> > 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.

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-* ?

Thank you.

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