u-boot/scripts/Makefile.host.tmp
Masahiro Yamada 9e4140329e kbuild: change out-of-tree build
This commit changes the working directory
where the build process occurs.

Before this commit, build process occurred under the source
tree for both in-tree and out-of-tree build.

That's why we needed to add $(obj) prefix to all generated
files in makefiles like follows:
  $(obj)u-boot.bin:  $(obj)u-boot

Here, $(obj) is empty for in-tree build, whereas it points
to the output directory for out-of-tree build.

And our old build system changes the current working directory
with "make -C <sub-dir>" syntax when descending into the
sub-directories.

On the other hand, Kbuild uses a different idea
to handle out-of-tree build and directory descending.

The build process of Kbuild always occurs under the output tree.
When "O=dir/to/store/output/files" is given, the build system
changes the current working directory to that directory and
restarts the make.

Kbuild uses "make -f $(srctree)/scripts/Makefile.build obj=<sub-dir>"
syntax for descending into sub-directories.
(We can write it like "make $(obj)=<sub-dir>" with a shorthand.)
This means the current working directory is always the top
of the output directory.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Gerhard Sittig <gsi@denx.de>
2014-02-19 11:07:50 -05:00

62 lines
2.1 KiB
Makefile

__hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
# C code
# Executables compiled from a single .c file
host-csingle := $(foreach m,$(__hostprogs),$(if $($(m)-objs),,$(m)))
# C executables linked based on several .o files
host-cmulti := $(foreach m,$(__hostprogs),$(if $($(m)-objs),$(m)))
# Object (.o) files compiled from .c files
host-cobjs := $(sort $(foreach m,$(__hostprogs),$($(m)-objs)))
# output directory for programs/.o files
# hostprogs-y := tools/build may have been specified. Retrieve directory
host-objdirs := $(foreach f,$(__hostprogs), $(if $(dir $(f)),$(dir $(f))))
# directory of .o files from prog-objs notation
host-objdirs += $(foreach f,$(host-cmulti), \
$(foreach m,$($(f)-objs), \
$(if $(dir $(m)),$(dir $(m)))))
host-objdirs := $(strip $(sort $(filter-out ./,$(host-objdirs))))
__hostprogs := $(addprefix $(obj)/,$(__hostprogs))
host-csingle := $(addprefix $(obj)/,$(host-csingle))
host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
host-cobjs := $(addprefix $(obj)/,$(host-cobjs))
host-objdirs := $(addprefix $(obj)/,$(host-objdirs))
obj-dirs += $(host-objdirs)
#####
# Handle options to gcc. Support building with separate output directory
_hostc_flags = $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) \
$(HOSTCFLAGS_$(basetarget).o)
# Find all -I options and call addtree
flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
ifeq ($(OBJTREE),$(SRCTREE))
__hostc_flags = $(_hostc_flags)
else
__hostc_flags = -I$(obj) $(call flags,_hostc_flags)
endif
hostc_flags = $(__hostc_flags)
#####
# Compile programs on the host
$(host-csingle): $(obj)/%: $(src)/%.c
$(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(HOSTLDFLAGS) $(HOSTCFLAGS_$(@F)) $(HOSTCFLAGS_$(BCURDIR)) -o $@ $<
$(host-cmulti): $(obj)/%: $(host-cobjs)
$(HOSTCC) $(HOSTLDFLAGS) -o $@ $(addprefix $(obj)/,$($(@F)-objs)) $(HOSTLOADLIBES_$(@F))
$(host-cobjs): $(obj)/%.o: $(src)/%.c
$(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(HOSTCFLAGS_$(@F)) $(HOSTCFLAGS_$(BCURDIR)) -o $@ $< -c
targets += $(host-csingle) $(host-cmulti) $(host-cobjs)