Re: perf BPF/elfdep intermitent build problems

["Wangnan (F)" <wangnan0@huawei.com>]

On 2015/11/19 10:21, Wangnan (F) wrote:
>
>
> On 2015/11/19 9:24, Wangnan (F) wrote:
>>
>>
>> On 2015/11/19 6:44, Arnaldo Carvalho de Melo wrote:
>>> Have you guys ever saw this?
>>>
>>> [acme@zoo linux]$ alias m
>>> alias m='perf stat -e cycles make O=/tmp/build/perf -C tools/perf
>>> install-bin'
>>> [acme @zoo linux]$ m
>>> make: Entering directory '/home/git/linux/tools/perf'
>>>    BUILD:   Doing 'make -j4' parallel build
>>> make[2]: Nothing to be done for 'fixdep'.
>>>    CC       /tmp/build/perf/util/machine.o
>>>    LD       /tmp/build/perf/util/libperf-in.o
>>> No libelf found
>>> BPF API too old
>>
>> This error message means the kernel header in rootfs is too old,
>> causes tools/build/feature/test-bpf.c failed to be built.
>
> Strange... even in feature detection it should check BPF API through
> kernel source where you are using to build perf...
>
> I guess you are not using NFS or share it with other people?
>
>>
>>> Makefile:191: recipe for target 'elfdep' failed
>>> make[2]: *** [elfdep] Error 255
>>> make[2]: *** Waiting for unfinished jobs....
>>> Makefile:194: recipe for target 'bpfdep' failed
>>> make[2]: *** [bpfdep] Error 255
>>> Makefile.perf:434: recipe for target '/tmp/build/perf/libbpf.a' failed
>>> make[1]: *** [/tmp/build/perf/libbpf.a] Error 2
>>> make[1]: *** Waiting for unfinished jobs....
>>>    LD       /tmp/build/perf/libperf-in.o
>>> Makefile:87: recipe for target 'install-bin' failed
>>> make: *** [install-bin] Error 2
>>> make: Leaving directory '/home/git/linux/tools/perf'
>>>
>>>   Performance counter stats for 'make O=/tmp/build/perf -C tools/perf
>>> install-bin':
>>>
>>>      10,265,920,369      cycles
>>>
>>>         3.002799545 seconds time elapsed
>>>
>>> [acme@zoo linux]$
>>>
>>>
>>> If I go and try doing a clean on the libbpf dir I see another problem:
>>>
>>> [acme@zoo linux]$ cd tools/lib/bpf
>>> [acme@zoo bpf]$ make clean
>>>
>>> Auto-detecting system features:
>>> ...                        libelf: [ OFF ]
>>> ...                           bpf: [ OFF ]
>>>
>>>    CLEAN    libbpf
>>>    CLEAN    core-gen
>>> [acme@zoo bpf]$
>>>
>>> No need for feature detection when doing a plain 'make clean', right?
>>>
>
> Right. It should be
>
> $ cd tools/lib/bpf
> $ make clean
>   CLEAN    libbpf
>   CLEAN    core-gen
> $
>
>
> After cleaning can you trigger this problem again?
>

Tiggered part of your problem:

$ make

Auto-detecting system features:
...                        libelf: [ on  ]
...                           bpf: [ on  ]

   CC       libbpf.o
   CC       bpf.o
   LD       libbpf-in.o
   LINK     libbpf.a
   LINK     libbpf.so
$ make clean
   CLEAN    libbpf
   CLEAN    core-gen
$ make clean

Auto-detecting system features:
...                        libelf: [ on  ]
...                           bpf: [ on  ]

   CLEAN    libbpf
   CLEAN    core-gen

Feature check would be triggered the second time we make clean.

Will look into it.

Thank you.