Switch from archive libraries to partial linking

Before this commit, weak symbols were not overridden by non-weak symbols
found in archive libraries when linking with recent versions of
binutils.  As stated in the System V ABI, "the link editor does not
extract archive members to resolve undefined weak symbols".

This commit changes all Makefiles to use partial linking (ld -r) instead
of creating library archives, which forces all symbols to participate in
linking, allowing non-weak symbols to override weak symbols as intended.
This approach is also used by Linux, from which the gmake function
cmd_link_o_target (defined in config.mk and used in all Makefiles) is
inspired.

The name of each former library archive is preserved except for
extensions which change from ".a" to ".o".  This commit updates
references accordingly where needed, in particular in some linker
scripts.

This commit reveals board configurations that exclude some features but
include source files that depend these disabled features in the build,
resulting in undefined symbols.  Known such cases include:
- disabling CMD_NET but not CMD_NFS;
- enabling CONFIG_OF_LIBFDT but not CONFIG_QE.

Signed-off-by: Sebastien Carlier <sebastien.carlier@gmail.com>

4 files changed, 8 insertions, 8 deletions

diff --git a/board/keymile/km8xx/Makefile b/board/keymile/km8xx/Makefile
index a6f32415aa0..abb9ef97244 100644
--- a/board/keymile/km8xx/Makefile
+++ b/board/keymile/km8xx/Makefile
@@ -26,7 +26,7 @@ ifneq ($(OBJTREE),$(SRCTREE))
 $(shell mkdir -p $(obj)../common)
 endif
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	= $(BOARD).o ../common/common.o ../common/keymile_hdlc_enet.o \
 		km8xx_hdlc_enet.o
@@ -36,7 +36,7 @@ OBJS	:= $(addprefix $(obj),$(COBJS))
 SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 #########################################################################
 
diff --git a/board/keymile/km_arm/Makefile b/board/keymile/km_arm/Makefile
index c5b0be16ef7..6bcfb257a8c 100644
--- a/board/keymile/km_arm/Makefile
+++ b/board/keymile/km_arm/Makefile
@@ -27,7 +27,7 @@ ifneq ($(OBJTREE),$(SRCTREE))
 $(shell mkdir -p $(obj)../common)
 endif
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= $(BOARD).o ../common/common.o
 
@@ -36,7 +36,7 @@ OBJS	:= $(addprefix $(obj),$(COBJS))
 SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
 $(LIB):	$(obj).depend $(OBJS) $(SOBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS) $(SOBJS)
+	$(call cmd_link_o_target, $(OBJS) $(SOBJS))
 
 clean:
 	rm -f $(SOBJS) $(OBJS)
diff --git a/board/keymile/kmeter1/Makefile b/board/keymile/kmeter1/Makefile
index 12a1518ff1a..2fa84f307a3 100644
--- a/board/keymile/kmeter1/Makefile
+++ b/board/keymile/kmeter1/Makefile
@@ -26,7 +26,7 @@ ifneq ($(OBJTREE),$(SRCTREE))
 $(shell mkdir -p $(obj)../common)
 endif
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	+= $(BOARD).o ../common/common.o
 
@@ -35,7 +35,7 @@ OBJS	:= $(addprefix $(obj),$(COBJS))
 SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 clean:
 	rm -f $(SOBJS) $(OBJS)
diff --git a/board/keymile/mgcoge/Makefile b/board/keymile/mgcoge/Makefile
index 2774a702b02..3308621a13d 100644
--- a/board/keymile/mgcoge/Makefile
+++ b/board/keymile/mgcoge/Makefile
@@ -26,7 +26,7 @@ ifneq ($(OBJTREE),$(SRCTREE))
 $(shell mkdir -p $(obj)../common)
 endif
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= $(BOARD).o ../common/common.o ../common/keymile_hdlc_enet.o \
 		mgcoge_hdlc_enet.o
@@ -36,7 +36,7 @@ OBJS	:= $(addprefix $(obj),$(COBJS))
 SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 clean:
 	rm -f $(SOBJS) $(OBJS)