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correct order of linker options to avoid link errors with recent toolchains

PATCH In review Olaf Hering 3 participants 5 messages Jul 23, 2010

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Olaf Hering

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#0 lore raw

PATCH 1/1 correct order of linker options to avoid link errors with recent toolchains

The order of objects and linked libraries is important with recent toolchain
when --as-needed is used. Move LDFLAGS to the end of cc commandline options. Without this change, symbols in libbzip2 are not found when building with openSuSE 11.2 and newer.

Signed-off-by Olaf Hering <[email protected]>

---

There are more places like this.
I will find and fix them when required.

 tools/libxc/Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
tools/libxc/Makefile +1 -1
@@ -181,7 +181,7 @@ xc_dom_bzimageloader.opic: CFLAGS += $(c
 
 libxenguest.so.$(MAJOR).$(MINOR): LDFLAGS += $(call zlib-options,l)
 libxenguest.so.$(MAJOR).$(MINOR): $(GUEST_PIC_OBJS) libxenctrl.so
-	$(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) -lz -lxenctrl $(PTHREAD_LIBS)
+	$(CC) $(CFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) $(LDFLAGS) -lz -lxenctrl $(PTHREAD_LIBS)
 
 -include $(DEPS)
#1 lore raw

Olaf Hering writes ("[Xen-devel] [PATCH] correct order of linker options to avoid link errors with recent toolchains"):

Quoted 3 lines

The order of objects and linked libraries is important with recent toolchain
when --as-needed is used. Move LDFLAGS to the end of cc commandline options. Without this change, symbols in libbzip2 are not found when building with openSuSE 11.2 and newer.

Thanks, but:

I infer that libbzip2 is in LDFLAGS (as -lbzip2, I guess). Is that right ? But I think that libraries should be in *_LIBS, not LDFLAGS. LDFLAGS needs to stay at the beginning so that it can work if you set it to -static or something.

Quoted 1 line

libxenguest.so.$(MAJOR).$(MINOR): LDFLAGS += $(call zlib-options,l)

What is this program "zlib-options" ? I don't have it on my system.

Ian.

#2 lore raw
Quoted 9 lines · Ian Jackson

Olaf Hering writes ("[Xen-devel] [PATCH] correct order of linker options to avoid link errors with recent toolchains"):

Quoted 4 lines

The order of objects and linked libraries is important with recent toolchain when --as-needed is used. Move LDFLAGS to the end of cc commandline options. Without this change, symbols in libbzip2 are not found when building with openSuSE 11.2 and newer.

Thanks, but:

Quoted 8 lines

I infer that libbzip2 is in LDFLAGS (as -lbzip2, I guess). Is that right ? But I think that libraries should be in *_LIBS, not LDFLAGS. LDFLAGS needs to stay at the beginning so that it can work if you set it to -static or something.

Quoted 1 line

libxenguest.so.$(MAJOR).$(MINOR): LDFLAGS += $(call zlib-options,l)

What is this program "zlib-options" ? I don't have it on my system.

It's right there in the same Makefile directly above the line you quoted. Yes, the above line can add -l<lib> items to LDFLAGS. Sounds like the right fix would indeed be to define a new COMPRESSION_LIBS variable and put it at the end of the linker command line.

-- Keir

#3 lore raw

Keir Fraser writes ("Re: [Xen-devel] [PATCH] correct order of linker options to avoid link errors with recent toolchains"):

Quoted 7 lines · Ian Jackson
Quoted 3 lines
Quoted 1 line

libxenguest.so.$(MAJOR).$(MINOR): LDFLAGS += $(call zlib-options,l)

What is this program "zlib-options" ? I don't have it on my system.

It's right there in the same Makefile directly above the line you quoted. Yes, the above line can add -l<lib> items to LDFLAGS.

Oh, duh. I'm confusing $(call ...) with $(shell ...) so I looked in entirely the wrong place.

Quoted 3 lines

Sounds like the right fix would indeed be to define a new
COMPRESSION_LIBS variable and put it at the end of the linker command line.

Yes. Olaf, would you like to provide a patch to do that ?

Ian.

author
#4 lore raw

PATCH 1/1 correct order of linker options to avoid link errors with recent toolchains

In reply to Olaf Hering

The order of objects and linked libraries is important with recent toolchain
when --as-needed is used.
Introduce new variable COMPRESSION_LIBS and place it at the end of cc commandline options. Without this change, symbols in libbzip2 are not found when building with openSuSE 11.2 and newer.

Signed-off-by Olaf Hering <[email protected]>

---
v2: use COMPRESSION_LIBS instead of moving LDFLAGS around

 tools/libxc/Makefile |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
tools/libxc/Makefile +2 -2
@@ -179,9 +179,9 @@ endif
 xc_dom_bzimageloader.o: CFLAGS += $(call zlib-options,D)
 xc_dom_bzimageloader.opic: CFLAGS += $(call zlib-options,D)
 
-libxenguest.so.$(MAJOR).$(MINOR): LDFLAGS += $(call zlib-options,l)
+libxenguest.so.$(MAJOR).$(MINOR): COMPRESSION_LIBS = $(call zlib-options,l)
 libxenguest.so.$(MAJOR).$(MINOR): $(GUEST_PIC_OBJS) libxenctrl.so
-	$(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) -lz -lxenctrl $(PTHREAD_LIBS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) $(COMPRESSION_LIBS) -lz -lxenctrl $(PTHREAD_LIBS)
 
 -include $(DEPS)