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SubjectRe: perf BPF/elfdep intermitent build problems


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?

>> But then, after cleaning it again, and entering tools/perf to do a 'make
>> clean' as well, it does the feature detection at a second 'make clean'
>> and this time it shoes [ on ] for both libelf and bpf, and this time
>> I manage to build perf.
>>
>> This is all intermitent, will eventually try to drill down if you don't
>> fix it first
>
> First let me try to trigger it in my environment...
>
> Thank you.
>
>> - Arnaldo
>
>
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