On Thu, Aug 08, 2013 at 09:13:38AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 8 Aug 2013, Simon Horman wrote:
>
> > When building ipvsadm this allows make to add to CFLAGS supplied
> > on the command line.
>
> Hm, the change below simply adds -I, variable
> override is already possible before the change. Is the
> commit correct?
The commit is completely wrong, sorry!
> > This seems to make sense as Makefile and libipvs/Makefile
> > add different CFLAGS but it may be desirable to supply supplementary
> > flags when building ipvsadm.
> >
> > In particular the following may be useful when building ipvsadm
> > on Debian Jessie.
> >
> > make CFLAGS='-I/usr/include/libnl3' LIBS='-lnl-3 -lnl-genl-3 -lnl-3 -lpopt'
>
> Hm, such command line vars override the
> vars in Makefiles, they do not add to them. So, it is
> not good for libipvs where -fPIC is the difference.
>
> make has such rules for vars:
>
> Order of variables:
> - command line
> - makefile
> - environment
>
> For example: var=env make var=command_line
> If -e is provided order is: command line, environment, makefile
> Sub-make: only command line and environment vars are inherited,
> use 'export' to provide variables defined in makefile
>
> As result, we can support EXTRA_CFLAGS when
> we want to add -Idir or other options, for example:
>
> Makefile:
> CFLAGS = $(EXTRA_CFLAGS) -Wall -Wunused -Wstrict-prototypes -g
>
> libipvs/Makefile:
> CFLAGS = $(EXTRA_CFLAGS) -Wall -Wunused -Wstrict-prototypes -g -fPIC
>
> Then:
>
> 1. Add to CFLAGS by providing EXTRA_CFLAGS, override LIBS:
>
> make EXTRA_CFLAGS='-I/usr/include/libnl3' \
> LIBS='-lnl-3 -lnl-genl-3 -lnl-3 -lpopt'
>
> 2. Override CFLAGS for both Makefiles because CFLAGS from
> command line is inherited in sub-make
>
> make CFLAGS='-I/usr/include/libnl3 -fPIC' \
> LIBS='-lnl-3 -lnl-genl-3 -lnl-3 -lpopt'
>
> We can add EXTRA_LIBS if needed to complement
> EXTRA_CFLAGS.
>
> Also, this is NOT an alternative:
>
> Makefile:
> CFLAGS+=-Wall -Wunused -Wstrict-prototypes -g
>
> Makefile:
> CFLAGS+=-Wall -Wunused -Wstrict-prototypes -g -fPIC
>
> because make CFLAGS=... will override the var,
> makefile can override command line vars in such way but
> it is ugly:
>
> override var=DEFERRED
> override var:=IMMEDIATE
> override var+=APPEND
I was planning to use override but somehow I sent the wrong version of the patch.
However, I like your EXTRA_CFLAGS and EXTRA_LIBS idea better.
Should I send a patch or would you like to?
>
> > Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
> > ---
> > Makefile | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 6e36d79..c8c1eec 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -48,7 +48,7 @@ STATIC_LIBS = libipvs/libipvs.a
> > ifeq "${ARCH}" "sparc64"
> > CFLAGS = -Wall -Wunused -Wstrict-prototypes -g -m64 -pipe -mcpu=ultrasparc -mcmodel=medlow
> > else
> > - CFLAGS = -Wall -Wunused -Wstrict-prototypes -g
> > + CFLAGS = -I/usr/include/libnl3 -Wall -Wunused -Wstrict-prototypes -g
> > endif
> >
> >
> > --
> > 1.8.3.2
>
> Regards
>
> --
> Julian Anastasov <ja@xxxxxx>
>
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