On Tue, 8 Oct 2013 12:11:20 +0200, Ingo Molnar wrote:
> If someone specifies a single target, mixed with O=, the following way:
>
> hubble:~/tip/tools/perf> make O=/tmp/perf util/stat.o
> BUILD: Doing 'make -j8' parallel build
> gcc -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security
> -Wformat-y2k [...]
>
> The build might even fail, if a target depends on other targets:
>
> hubble:~/tip/tools/perf> make O=/tmp/perf perf.o
> ...
> perf.c: In function ‘handle_options’:
> perf.c:155:21: error: ‘PERF_HTML_PATH’ undeclared (first use in this
> function)
>
> The correct way to invoke such targets is:
>
> hubble:~/tip/tools/perf> make O=/tmp/perf /tmp/perf/perf.o
> BUILD: Doing 'make -j8' parallel build
> GEN /tmp/perf/common-cmds.h
> CC /tmp/perf/perf.o
>
> But that's unnecessary typing and it's also easy to mistakenly build into the
> source directory.
>
> To fix this remove the generic suffix rules and add redirection to $(OUTPUT)
> for the most popular .o targets.
I got this:
$ cd tools/perf
$ make
... (succeeded)
$ make O=~/build/perf perf.o
make: `perf.o' is up to date.
$ rm ~/build/perf/perf.o
$ make O=~/build/perf/ perf.o
make: `perf.o' is up to date.
> +#
> +# If a target does not match any of the later rules then prefix it by
> $(OUTPUT)
> +# This makes targets like 'make O=/tmp/perf perf.o' work in a natural way.
> +#
> +ifneq ($(OUTPUT),)
> +%.o: $(OUTPUT)%.o
> + @echo " # Redirected target $@ => $(OUTPUT)$@"
> +util/%.o: $(OUTPUT)util/%.o
> + @echo " # Redirected target $@ => $(OUTPUT)util/$@"
> +bench/%.o: $(OUTPUT)bench/%.o
> + @echo " # Redirected target $@ => $(OUTPUT)bench/$@"
> +tests/%.o: $(OUTPUT)tests/%.o
> + @echo " # Redirected target $@ => $(OUTPUT)tests/$@"
> +endif
It also doesn't care about other directories - arch/, scripts/ and ui/ -
and their subdirectories. So even on clean build it'll failed to build
these files with O=dir.
$ make clean
$ make O=~/build/perf ui/stdio/hist.o
BUILD: Doing 'make -j12' parallel build
make[1]: *** No rule to make target `ui/stdio/hist.o'. Stop.
make: *** [ui/stdio/hist.o] Error 2
Thanks,
Namhyung
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