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Date:   Thu, 22 Mar 2018 19:13:31 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     sztsian@gmail.com
Cc:     johannes.berg@intel.com, johannes@sipsolutions.net,
        linux-kernel@vger.kernel.org, zsun@redhat.com
Subject: Re: [PATCH 2/2] trace-cmd: Change the way of getting python
 ldflags.
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In-Reply-To: <20180204032014.6962-3-sztsian@gmail.com>
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        <20180204032014.6962-3-sztsian@gmail.com>
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On Sun,  4 Feb 2018 11:20:14 +0800
sztsian@gmail.com wrote:

> From: Zamir SUN <sztsian@gmail.com>
> 
> Prior than this patch, Makefile detects python ldflags using a hardcoded
> python command. It will cause problems if we are building against
> python3 in the future when ldflags for python2 and python3 are
> different. With this patch, python ldflags are detected by
> corresponding python{,3}-config which will detect the right config for
> python plugins.
> 
> Signed-off-by: Zamir SUN (Red Hat) <sztsian@gmail.com>
> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index 7c0d1a6..f41e399 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -636,7 +636,7 @@ report_noswig: force
>  
>  PYTHON_INCLUDES = `pkg-config --cflags $(PYTHON_VERS)`
>  PYTHON_LDFLAGS = `pkg-config --libs $(PYTHON_VERS)` \
> -		$(shell python2 -c "import distutils.sysconfig; print distutils.sysconfig.get_config_var('LINKFORSHARED')")
> +		$(shell $(PYTHON_VERS)-config --ldflags)
>  PYGTK_CFLAGS = `pkg-config --cflags pygtk-2.0`
>  
>  ctracecmd.so: $(TCMD_LIB_OBJS) ctracecmd.i

BTW, I did have this applied, but when testing it caused warnings. I
had to apply this patch to fix it:

-- Steve

From d5579b729114135da20bcee6896a0683ff54f33a Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Thu, 22 Mar 2018 18:38:22 -0400
Subject: [PATCH] trace-cmd build: Do not execute python scripts if there is no
 python

I was triggering the following build messages when not having swig installed:

make: -config: Command not found

    NO_PYTHON forced: swig not installed, not compiling python plugins

make: -config: Command not found
  UPDATE                 trace_python_dir
make: -config: Command not found

This is due to the executing of $(PYTHON_VERS)-config, which would just turn
into "-config". Do not assign the PYTHON_* variables if NO_PYTHON is
defined.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Makefile b/Makefile
index 2c82301..26fd42b 100644
--- a/Makefile
+++ b/Makefile
@@ -373,10 +373,16 @@ report_nopythondev: force
 	$(Q)echo "    python-dev is not installed, not compiling python plugins"
 	$(Q)echo
 
+ifndef NO_PYTHON
 PYTHON_INCLUDES = `pkg-config --cflags $(PYTHON_VERS)`
 PYTHON_LDFLAGS = `pkg-config --libs $(PYTHON_VERS)` \
 		$(shell $(PYTHON_VERS)-config --ldflags)
 PYGTK_CFLAGS = `pkg-config --cflags pygtk-2.0`
+else
+PYTHON_INCLUDES =
+PYTHON_LDFLAGS =
+PYGTK_CFLAGS =
+endif
 
 export PYTHON_INCLUDES
 export PYTHON_LDFLAGS
-- 
2.13.6