Makefile: be more friendly with user supplied CFLAGS

Makefile: be more friendly with user supplied CFLAGS

[Uwe Kleine-König]

For compilation to work

	-D_GNU_SOURCE -Isrc/include

is needed to be passed to the compiler. For Debian packaging several
things are added but not these two from above. So be a bit more friendly
and add them unconditionally. There is no harm if they are included in
the user supplied CFLAGS and so passed twice.

Moreover be a bit more correct about CFLAGS/CPPFLAGS. Both should be
passed to the compiler with CFLAGS taking options for the compiler and
CPPFLAGS taking options for the preprocessor. This is also needed for
Debian packaging where the helper scripts set CPPFLAGS.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 
---
 Makefile |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: rt-tests/Makefile
===================================================================
--- rt-tests.orig/Makefile	2012-09-02 22:04:06.547562496 +0200
+++ rt-tests/Makefile	2012-09-02 22:06:56.169496678 +0200
@@ -20,7 +20,8 @@
 NUMA 	:= 1
 endif
 
-CFLAGS ?= -D_GNU_SOURCE -Wall -Wno-nonnull -Isrc/include
+CFLAGS ?= -Wall -Wno-nonnull
+CPPFLAGS += -D_GNU_SOURCE -Isrc/include
 LDFLAGS ?=
 
 ifndef DEBUG
@@ -47,7 +48,7 @@
 VPATH	+= src/hackbench
 
 %.o: %.c
-	$(CC) -D VERSION_STRING=$(VERSION_STRING) -c $< $(CFLAGS)
+	$(CC) -D VERSION_STRING=$(VERSION_STRING) -c $< $(CFLAGS) $(CPPFLAGS)
 
 # Pattern rule to generate dependency files from .c files
 %.d: %.c
--
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Re: Makefile: be more friendly with user supplied CFLAGS

[John Kacur]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2945 bytes --]

Your Subject lines need to be improved. First of all, can you preface them 
with something like [PATCH RT-TESTS]? Second, your descriptions are not 
good. I have also been accused of having poor descriptions, so you are not 
alone in this. However, "be more friendly" - that is not exactly a good 
technical description. Something like, "Separate CFLAGS and CPPFLAGS" 
would be better in my opinion.

Did you test this?!!!

I get errors like this
src/pi_tests/pip_stress.c:57:24: fatal error: pip_stress.h: No such file 
or directory

I believe you just need to add CPPFLAGS to the dependency part like this
B 
diff --git a/Makefile b/Makefile
index a6f7a1b..33e8d60 100644
--- a/Makefile
+++ b/Makefile
@@ -54,7 +54,7 @@ VPATH += src/hackbench
 
 # Pattern rule to generate dependency files from .c files
 %.d: %.c
-       @$(CC) -MM $(CFLAGS) $< | sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' > $@ 
|| rm
+       @$(CC) -MM $(CFLAGS) $(CPPFLAGS) $< | sed 's,\($*\)\.o[ :]*,\1.o 
$@ : ,g
 
 .PHONY: all
 all: $(TARGETS) hwlatdetect

Finally, I'm not sure I understand the benefit of separating the two, why 
do we need this? What is improved? Are you saying that the Debian build 
system breaks without it?

Thanks

John

On Sun, 2 Sep 2012, Uwe Kleine-König wrote:

> For compilation to work
> 
> 	-D_GNU_SOURCE -Isrc/include
> 
> is needed to be passed to the compiler. For Debian packaging several
> things are added but not these two from above. So be a bit more friendly
> and add them unconditionally. There is no harm if they are included in
> the user supplied CFLAGS and so passed twice.
> 
> Moreover be a bit more correct about CFLAGS/CPPFLAGS. Both should be
> passed to the compiler with CFLAGS taking options for the compiler and
> CPPFLAGS taking options for the preprocessor. This is also needed for
> Debian packaging where the helper scripts set CPPFLAGS.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 
> ---
>  Makefile |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> Index: rt-tests/Makefile
> ===================================================================
> --- rt-tests.orig/Makefile	2012-09-02 22:04:06.547562496 +0200
> +++ rt-tests/Makefile	2012-09-02 22:06:56.169496678 +0200
> @@ -20,7 +20,8 @@
>  NUMA 	:= 1
>  endif
>  
> -CFLAGS ?= -D_GNU_SOURCE -Wall -Wno-nonnull -Isrc/include
> +CFLAGS ?= -Wall -Wno-nonnull
> +CPPFLAGS += -D_GNU_SOURCE -Isrc/include
>  LDFLAGS ?=
>  
>  ifndef DEBUG
> @@ -47,7 +48,7 @@
>  VPATH	+= src/hackbench
>  
>  %.o: %.c
> -	$(CC) -D VERSION_STRING=$(VERSION_STRING) -c $< $(CFLAGS)
> +	$(CC) -D VERSION_STRING=$(VERSION_STRING) -c $< $(CFLAGS) $(CPPFLAGS)
>  
>  # Pattern rule to generate dependency files from .c files
>  %.d: %.c
> --
> To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>