Re: perf BPF/elfdep intermitent build problems

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

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.

> 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?
>
> 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