u-boot/examples/standalone/Makefile
Sebastien Carlier 6d8962e814 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>
2010-11-17 21:02:18 +01:00

117 lines
3.6 KiB
Makefile

#
# (C) Copyright 2000-2006
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# See file CREDITS for list of people who contributed to this
# project.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
include $(TOPDIR)/config.mk
ELF-$(ARCH) :=
ELF-$(BOARD) :=
ELF-$(CPU) :=
ELF-y := hello_world
ELF-$(CONFIG_SMC91111) += smc91111_eeprom
ELF-$(CONFIG_SMC911X) += smc911x_eeprom
ELF-$(CONFIG_SPI_FLASH_ATMEL) += atmel_df_pow2
ELF-i386 += 82559_eeprom
ELF-mpc5xxx += interrupt
ELF-mpc8xx += test_burst timer
ELF-mpc8260 += mem_to_mem_idma2intr
ELF-ppc += sched
ELF-oxc += eepro100_eeprom
#
# Some versions of make do not handle trailing white spaces properly;
# leading to build failures. The problem was found with GNU Make 3.80.
# Using 'strip' as a workaround for the problem.
#
ELF := $(strip $(ELF-y) $(ELF-$(ARCH)) $(ELF-$(BOARD)) $(ELF-$(CPU)))
SREC = $(addsuffix .srec,$(ELF))
BIN = $(addsuffix .bin,$(ELF))
COBJS := $(ELF:=.o)
LIB = $(obj)libstubs.o
LIBAOBJS-$(ARCH) :=
LIBAOBJS-$(CPU) :=
LIBAOBJS-ppc += $(ARCH)_longjmp.o $(ARCH)_setjmp.o
LIBAOBJS-mpc8xx += test_burst_lib.o
LIBAOBJS := $(LIBAOBJS-$(ARCH)) $(LIBAOBJS-$(CPU))
LIBCOBJS = stubs.o
LIBOBJS = $(addprefix $(obj),$(LIBAOBJS) $(LIBCOBJS))
SRCS := $(COBJS:.o=.c) $(LIBCOBJS:.o=.c) $(LIBAOBJS:.o=.S)
OBJS := $(addprefix $(obj),$(COBJS))
ELF := $(addprefix $(obj),$(ELF))
BIN := $(addprefix $(obj),$(BIN))
SREC := $(addprefix $(obj),$(SREC))
gcclibdir := $(shell dirname `$(CC) -print-libgcc-file-name`)
CPPFLAGS += -I..
# For PowerPC there's no need to compile standalone applications as a
# relocatable executable. The relocation data is not needed, and
# also causes the entry point of the standalone application to be
# inconsistent.
ifeq ($(ARCH),powerpc)
AFLAGS := $(filter-out $(RELFLAGS),$(AFLAGS))
CFLAGS := $(filter-out $(RELFLAGS),$(CFLAGS))
CPPFLAGS := $(filter-out $(RELFLAGS),$(CPPFLAGS))
endif
# We don't want gcc reordering functions if possible. This ensures that an
# application's entry point will be the first function in the application's
# source file.
CFLAGS += $(call cc-option,-fno-toplevel-reorder)
all: $(obj).depend $(OBJS) $(LIB) $(SREC) $(BIN) $(ELF)
#########################################################################
$(LIB): $(obj).depend $(LIBOBJS)
$(call cmd_link_o_target, $(LIBOBJS))
$(ELF):
$(obj)%: $(obj)%.o $(LIB)
$(LD) -g -Ttext $(STANDALONE_LOAD_ADDR) \
-o $@ -e $(SYM_PREFIX)$(notdir $(<:.o=)) $< $(LIB) \
-L$(gcclibdir) -lgcc
$(SREC):
$(obj)%.srec: $(obj)%
$(OBJCOPY) -O srec $< $@ 2>/dev/null
$(BIN):
$(obj)%.bin: $(obj)%
$(OBJCOPY) -O binary $< $@ 2>/dev/null
#########################################################################
# defines $(obj).depend target
include $(SRCTREE)/rules.mk
sinclude $(obj).depend
#########################################################################