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>

5 files changed, 10 insertions, 10 deletions

diff --git a/board/logicpd/am3517evm/Makefile b/board/logicpd/am3517evm/Makefile
index 3a6b1a11c10..83fab0e4fdc 100644
--- a/board/logicpd/am3517evm/Makefile
+++ b/board/logicpd/am3517evm/Makefile
@@ -22,7 +22,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= am3517evm.o
 
@@ -30,7 +30,7 @@ SRCS	:= $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 clean:
 	rm -f $(OBJS)
diff --git a/board/logicpd/imx27lite/Makefile b/board/logicpd/imx27lite/Makefile
index 04dc8ae1fd9..944434bb933 100644
--- a/board/logicpd/imx27lite/Makefile
+++ b/board/logicpd/imx27lite/Makefile
@@ -23,7 +23,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= imx27lite.o
 SOBJS	:= lowlevel_init.o
@@ -33,7 +33,7 @@ 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/logicpd/imx31_litekit/Makefile b/board/logicpd/imx31_litekit/Makefile
index 218d9684a12..e604c31b193 100644
--- a/board/logicpd/imx31_litekit/Makefile
+++ b/board/logicpd/imx31_litekit/Makefile
@@ -23,7 +23,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= imx31_litekit.o
 SOBJS	:= lowlevel_init.o
@@ -33,7 +33,7 @@ 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/logicpd/zoom1/Makefile b/board/logicpd/zoom1/Makefile
index 9e87f173953..75085b4e16b 100644
--- a/board/logicpd/zoom1/Makefile
+++ b/board/logicpd/zoom1/Makefile
@@ -23,7 +23,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS	:= zoom1.o
 
@@ -31,7 +31,7 @@ SRCS	:= $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 clean:
 	rm -f $(OBJS)
diff --git a/board/logicpd/zoom2/Makefile b/board/logicpd/zoom2/Makefile
index 2feafbee1df..17f595e72c6 100644
--- a/board/logicpd/zoom2/Makefile
+++ b/board/logicpd/zoom2/Makefile
@@ -23,7 +23,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= $(obj)lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).o
 
 COBJS-y := $(BOARD).o
 COBJS-y += debug_board.o
@@ -35,7 +35,7 @@ SRCS	:= $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 clean:
 	rm -f $(OBJS)