Re: [PATCH v2 2/2] perf tools: Default to python version 2

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Jul 29, 2014 at 03:57:20PM +0900, Namhyung Kim escreveu:
> According to PEP 394 recommendation [1], it's more portable to use
> python2 rather than plain python to refer python binary version 2.
> 
> Since there're distros using python3 by default like Arch, and we
> don't support python3 (yet), it'd be better using python2 explicitly.
> 
> But older versions (prior to 2.7) seem not to provide python2 but just
> python.  Given that it's only old version, try python2 first and then
> fallback to python.  It'll ensure that it always points to python 2.x.

It should fallback, right?

[acme@fedora14 linux]$ ls -la /usr/bin/python2-config
ls: cannot access /usr/bin/python2-config: No such file or directory
[acme@fedora14 linux]$ ls -la /usr/bin/python-config
lrwxrwxrwx. 1 root root 16 Mar 25 09:43 /usr/bin/python-config -> python2.7-config
[acme@fedora14 linux]$ rpm -qf /usr/bin/python-config 
python-devel-2.7-8.fc14.1.x86_64
[acme@fedora14 linux]$ cat /etc/fedora-release 
Fedora release 14 (Laughlin)
[acme@fedora14 linux]$ 

[acme@fedora14 linux]$ time make O=/tmp/build/perf -C tools/perf install
make: Entering directory `/home/acme/git/linux/tools/perf'
  BUILD:   Doing 'make -j4' parallel build
config/Makefile:126: The path '/usr/bin/python2-config' is not executable.
config/Makefile:339: No libdw DWARF unwind found, Please install
elfutils-devel/libdw-dev >= 0.158 and/or set LIBDW_DIR
config/Makefile:481: Missing perl devel files. Disabling perl scripting
support, consider installing perl-ExtUtils-Embed
config/Makefile:512: No python-config tool was found
config/Makefile:512: Python support will not be built
 
> [1] https://www.python.org/dev/peps/pep-0394
> 
> Suggested-by: Thomas Ilsche <thomas.ilsche@tu-dresden.de>
> Tested-by: Thomas Ilsche <thomas.ilsche@tu-dresden.de>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/config/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> index e05d8f99424d..60177278a357 100644
> --- a/tools/perf/config/Makefile
> +++ b/tools/perf/config/Makefile
> @@ -121,8 +121,8 @@ ifdef PARSER_DEBUG
>  endif
>  
>  ifndef NO_LIBPYTHON
> -  override PYTHON := \
> -    $(call get-executable-or-default,PYTHON,python)
> +  PYTHON2 := $(if $(call get-executable,python2),python2,python)
> +  override PYTHON := $(call get-executable-or-default,PYTHON,$(PYTHON2))
>    override PYTHON_CONFIG := \
>      $(call get-executable-or-default,PYTHON_CONFIG,$(PYTHON)-config)
>  
> -- 
> 2.0.0