u-boot/examples/standalone/Makefile
Masahiro Yamada c16b137e49 kbuild: add .SECONDARY special target to scripts/Kbuild.include
Based on the following Linux commits:

 - 54a702f70589 ("kbuild: mark $(targets) as .SECONDARY and remove
   .PRECIOUS markers")

 - 8e9b61b293d9 ("kbuild: move .SECONDARY special target to
   Kbuild.include")

GNU Make automatically deletes intermediate files that are updated
in a chain of pattern rules.

Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
Example 2) %.o <- %.c <- %.c_shipped

A couple of makefiles mark such targets as .PRECIOUS to prevent Make
from deleting them, but the correct way is to use .SECONDARY.

  .SECONDARY
    Prerequisites of this special target are treated as intermediate
    files but are never automatically deleted.

  .PRECIOUS
    When make is interrupted during execution, it may delete the target
    file it is updating if the file was modified since make started.
    If you mark the file as precious, make will never delete the file
    if interrupted.

Both can avoid deletion of intermediate files, but the difference is
the behavior when Make is interrupted; .SECONDARY deletes the target,
but .PRECIOUS does not.

The use of .PRECIOUS is relatively rare since we do not want to keep
partially constructed (possibly corrupted) targets.

.SECONDARY with no prerequisites causes all targets to be treated as
secondary. This agrees the policy of Kbuild.

scripts/Kbuild.include seems a suitable place to add it because it is
included from almost all sub-makes.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-01-15 15:28:53 -05:00

80 lines
2.3 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0+
#
# (C) Copyright 2000-2006
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
extra-y := hello_world
extra-$(CONFIG_SMC91111) += smc91111_eeprom
extra-$(CONFIG_SMC911X) += smc911x_eeprom
extra-$(CONFIG_SPI_FLASH_ATMEL) += atmel_df_pow2
extra-$(CONFIG_PPC) += sched
#
# 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 $(extra-y))
extra-y += $(addsuffix .srec,$(extra-y)) $(addsuffix .bin,$(extra-y))
clean-files := *.srec *.bin
COBJS := $(ELF:=.o)
LIB = $(obj)/libstubs.o
LIBOBJS-$(CONFIG_PPC) += ppc_longjmp.o ppc_setjmp.o
LIBOBJS-y += stubs.o
targets += $(patsubst $(obj)/%,%,$(LIB)) $(COBJS) $(LIBOBJS-y)
LIBOBJS := $(addprefix $(obj)/,$(LIBOBJS-y))
ELF := $(addprefix $(obj)/,$(ELF))
# 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 ($(CONFIG_PPC),y)
PLATFORM_CPPFLAGS := $(filter-out $(RELFLAGS),$(PLATFORM_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.
ccflags-y += $(call cc-option,-fno-toplevel-reorder)
LDFLAGS_STANDALONE += -Ttext $(CONFIG_STANDALONE_LOAD_ADDR)
#########################################################################
quiet_cmd_link_lib = LD $@
cmd_link_lib = $(LD) $(ld_flags) -r -o $@ $(filter $(LIBOBJS), $^)
$(LIB): $(LIBOBJS) FORCE
$(call if_changed,link_lib)
quiet_cmd_link_elf = LD $@
cmd_link_elf = $(LD) $(LDFLAGS) $(LDFLAGS_STANDALONE) -g \
-o $@ -e $(SYM_PREFIX)$(@F) $< $(LIB) $(PLATFORM_LIBGCC)
$(ELF): $(obj)/%: $(obj)/%.o $(LIB) FORCE
$(call if_changed,link_elf)
$(obj)/%.srec: OBJCOPYFLAGS += -O srec
$(obj)/%.srec: $(obj)/% FORCE
$(call if_changed,objcopy)
$(obj)/%.bin: OBJCOPYFLAGS += -O binary
$(obj)/%.bin: $(obj)/% FORCE
$(call if_changed,objcopy)
# some files can only build in ARM or THUMB2, not THUMB1
ifdef CONFIG_SYS_THUMB_BUILD
ifndef CONFIG_HAS_THUMB2
CFLAGS_stubs.o := -marm
endif
endif