[dpdk-dev] [PATCH] mk: add EXTRA_CFLAGS to link step for shared library

[dpdk-dev] [PATCH] mk: add EXTRA_CFLAGS to link step for shared library

[Stephen Hemminger]

When doing a cross compiling it is common to use EXTRA_CFLAGS with
--sysroot option to point to alternate root filesystem. This already
works as expected for objects and executables, it just doesn't work
correctly for shared libraries.

When a shared library is linked using CC this flag needs to
be passed in order for libraries to be found.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 mk/rte.shared.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mk/rte.shared.mk b/mk/rte.shared.mk
index 2b501ddb8480..a0620a3eb233 100644
--- a/mk/rte.shared.mk
+++ b/mk/rte.shared.mk
@@ -31,7 +31,7 @@ exe2cmd = $(strip $(call dotfile,$(patsubst %,%.cmd,$(1))))
 
 ifeq ($(LINK_USING_CC),1)
 override EXTRA_LDFLAGS := $(call linkerprefix,$(EXTRA_LDFLAGS))
-O_TO_SO = $(CC) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
+O_TO_SO = $(CC) $(EXTRA_CFLAGS) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
 	-shared -o $@ $(OBJS-y) $(call linkerprefix,$(LDLIBS))
 else
 O_TO_SO = $(LD) $(LDFLAGS) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
-- 
2.20.1

Re: [dpdk-dev] [PATCH] mk: add EXTRA_CFLAGS to link step for shared library

[Thomas Monjalon]

05/11/2019 02:56, Stephen Hemminger:
> When doing a cross compiling it is common to use EXTRA_CFLAGS with
> --sysroot option to point to alternate root filesystem. This already
> works as expected for objects and executables, it just doesn't work
> correctly for shared libraries.
> 
> When a shared library is linked using CC this flag needs to
> be passed in order for libraries to be found.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> --- a/mk/rte.shared.mk
> +++ b/mk/rte.shared.mk
> -O_TO_SO = $(CC) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
> +O_TO_SO = $(CC) $(EXTRA_CFLAGS) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
>  	-shared -o $@ $(OBJS-y) $(call linkerprefix,$(LDLIBS))

After several thoughts, I am afraid of the possible side effects
of such a change.
I think only LDFLAGS should be used when linking.
If you need the same parameters at compilation and linking,
you should pass the same parameters to CFLAGS and LDFLAGS.

Re: [dpdk-dev] [PATCH] mk: add EXTRA_CFLAGS to link step for shared library

[Stephen Hemminger]

On Mon, 25 Nov 2019 23:56:00 +0100
Thomas Monjalon <thomas@monjalon.net> wrote:

> 05/11/2019 02:56, Stephen Hemminger:
> > When doing a cross compiling it is common to use EXTRA_CFLAGS with
> > --sysroot option to point to alternate root filesystem. This already
> > works as expected for objects and executables, it just doesn't work
> > correctly for shared libraries.
> > 
> > When a shared library is linked using CC this flag needs to
> > be passed in order for libraries to be found.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> > --- a/mk/rte.shared.mk
> > +++ b/mk/rte.shared.mk
> > -O_TO_SO = $(CC) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
> > +O_TO_SO = $(CC) $(EXTRA_CFLAGS) $(call linkerprefix,$(LDFLAGS)) $(LDFLAGS_$(@)) $(EXTRA_LDFLAGS) \
> >  	-shared -o $@ $(OBJS-y) $(call linkerprefix,$(LDLIBS))  
> 
> After several thoughts, I am afraid of the possible side effects
> of such a change.
> I think only LDFLAGS should be used when linking.
> If you need the same parameters at compilation and linking,
> you should pass the same parameters to CFLAGS and LDFLAGS.

Let me try same thing with EXTRA_LDFLAGS