* Ingo Molnar <mi...@kernel.org> wrote:
> Now it displays the spammy auto-detection all the time:
>
> comet:~/tip/tools/perf> make
> BUILD: Doing 'make -j12' parallel build
>
> Auto-detecting system features:
> ... backtrace: [ on ]
> ... dwarf: [ on ]
> ... fortify-source: [ on ]
> ... glibc: [ on ]
> ... gtk2: [ on ]
> ... gtk2-infobar: [ on ]
> ... libaudit: [ on ]
> ... libbfd: [ on ]
> ... libelf: [ on ]
> ... libelf-getphdrnum: [ on ]
> ... libelf-mmap: [ on ]
> ... libnuma: [ on ]
> ... libperl: [ on ]
> ... libpython: [ on ]
> ... libpython-version: [ on ]
> ... libslang: [ on ]
> ... libunwind: [ on ]
> ... on-exit: [ on ]
> ... stackprotector: [ on ]
> ... stackprotector-all: [ on ]
>
> maybe a new testcase fails on my box, but is not properly displayed?
Hm, a 'make clean' cleaned up the condition and it now works as expected.
So what happened is that GCC got upgraded from 4.8.1 to 4.8.2 and
test-all.c failed to build:
comet:~/tip/tools/perf/config/feature-checks> make -i
make: *** No rule to make target
`/usr/lib/gcc/x86_64-redhat-linux/4.8.1/include/limits.h', needed by
`test-all'. Stop.
but the individual testcases got built successfully and the perf build was
fine and correct - it's just that the test-all.c .d file never got updated
due to the broken dependency.
I think Namhyung warned about this during the feature-detection
discussion, and I dismissed the concern - but Namhyung was right, it's a
real problem.
I think to fix this we should automatically clean out potentially stale .d
files automatically after testcase build failures (be it test-all.c or any
other testcase)?
That would still preserve all the good roles of these dependencies and it
would preserve the build speed and detection of system library changes.
Thanks,
Ingo
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