configuration.
Kbuild compiles all the $(obj-y) files. It then calls
- "$(AR) rcSTP" to merge these files into one built-in.o file.
+ "$(AR) rcSTP" to merge these files into one built-in.a file.
This is a thin archive without a symbol table, which makes it
unsuitable as a linker input.
The scripts/link-vmlinux.sh script later makes an aggregate
- built-in.o with "${AR} rcsTP", which creates the thin archive
+ built-in.a with "${AR} rcsTP", which creates the thin archive
with a symbol table and an index, making it a valid input for
the final vmlinux link passes.
The order of files in $(obj-y) is significant. Duplicates in
the lists are allowed: the first instance will be linked into
- built-in.o and succeeding instances will be ignored.
+ built-in.a and succeeding instances will be ignored.
Link order is significant, because certain functions
(module_init() / __initcall) will be called during boot in the
Note: Of course, when you are building objects into the kernel,
the syntax above will also work. So, if you have CONFIG_EXT2_FS=y,
kbuild will build an ext2.o file for you out of the individual
- parts and then link this into built-in.o, as you would expect.
+ parts and then link this into built-in.a, as you would expect.
--- 3.4 Objects which export symbols
--- 3.5 Library file goals - lib-y
Objects listed with obj-* are used for modules, or
- combined in a built-in.o for that specific directory.
+ combined in a built-in.a for that specific directory.
There is also the possibility to list objects that will
be included in a library, lib.a.
All objects listed with lib-y are combined in a single
Note that the same kbuild makefile may list files to be built-in
and to be part of a library. Therefore the same directory
- may contain both a built-in.o and a lib.a file.
+ may contain both a built-in.a and a lib.a file.
Example:
#arch/x86/lib/Makefile
$(head-y) lists objects to be linked first in vmlinux.
$(libs-y) lists directories where a lib.a archive can be located.
- The rest list directories where a built-in.o object file can be
+ The rest list directories where a built-in.a object file can be
located.
$(init-y) objects will be located after $(head-y).
extra-y := head.o init_task.o
In this example, extra-y is used to list object files that
- shall be built, but shall not be linked as part of built-in.o.
+ shall be built, but shall not be linked as part of built-in.a.
--- 6.7 Commands useful for building a boot image
# Most importantly: sub-Makefiles should only ever modify files in
# their own directory. If in some directory we have a dependency on
# a file in another dir (which doesn't happen often, but it's often
-# unavoidable when linking the built-in.o targets which finally
+# unavoidable when linking the built-in.a targets which finally
# turn into vmlinux), we will call a sub make in that other dir, and
# after that we are sure that everything which is in that other dir
# is now up to date.
vmlinux-alldirs := $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
$(init-) $(core-) $(drivers-) $(net-) $(libs-) $(virt-))))
-init-y := $(patsubst %/, %/built-in.o, $(init-y))
-core-y := $(patsubst %/, %/built-in.o, $(core-y))
-drivers-y := $(patsubst %/, %/built-in.o, $(drivers-y))
-net-y := $(patsubst %/, %/built-in.o, $(net-y))
+init-y := $(patsubst %/, %/built-in.a, $(init-y))
+core-y := $(patsubst %/, %/built-in.a, $(core-y))
+drivers-y := $(patsubst %/, %/built-in.a, $(drivers-y))
+net-y := $(patsubst %/, %/built-in.a, $(net-y))
libs-y1 := $(patsubst %/, %/lib.a, $(libs-y))
-libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.o, $(libs-y)))
-virt-y := $(patsubst %/, %/built-in.o, $(virt-y))
+libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
+virt-y := $(patsubst %/, %/built-in.a, $(virt-y))
# Externally visible symbols (used by link-vmlinux.sh)
export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
/*
* Because string functions are both inline and exported functions and
* folder arch/blackfin/lib is configured as a library path in Makefile,
- * symbols exported in folder lib is not linked into built-in.o but
+ * symbols exported in folder lib is not linked into built-in.a but
* inlined only. In order to export string symbols to kernel module
* properly, they should be exported here.
*/
$(call cmd,systbl_chk)
ifeq ($(CONFIG_PPC_OF_BOOT_TRAMPOLINE),y)
-$(obj)/built-in.o: prom_init_check
+$(obj)/built-in.a: prom_init_check
quiet_cmd_prom_init_check = CALL $<
cmd_prom_init_check = $(CONFIG_SHELL) $< "$(NM)" "$(obj)/prom_init.o"
obj-y += cio/ block/ char/ crypto/ net/ scsi/ virtio/
-drivers-y += drivers/s390/built-in.o
+drivers-y += drivers/s390/built-in.a
the analysis would not catch the illegal reference.
This option tells gcc to inline less (but it does result in
a larger kernel).
- - Run the section mismatch analysis for each module/built-in.o file.
+ - Run the section mismatch analysis for each module/built-in.a file.
When we run the section mismatch analysis on vmlinux.o, we
lose valueble information about where the mismatch was
introduced.
- Running the analysis for each module/built-in.o file
+ Running the analysis for each module/built-in.a file
tells where the mismatch happens much closer to the
source. The drawback is that the same mismatch is
reported at least twice.
endif
ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
-builtin-target := $(obj)/built-in.o
+builtin-target := $(obj)/built-in.a
endif
modorder-target := $(obj)/modules.order
endif
endif
-# Do section mismatch analysis for each module/built-in.o
+# Do section mismatch analysis for each module/built-in.a
ifdef CONFIG_DEBUG_SECTION_MISMATCH
cmd_secanalysis = ; scripts/mod/modpost $@
endif
#
ifdef builtin-target
-# built-in.o archives are made with no symbol table or index which
+# built-in.a archives are made with no symbol table or index which
# makes them small and fast, but unable to be used by the linker.
-# scripts/link-vmlinux.sh builds an aggregate built-in.o with a symbol
+# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol
# table and index.
cmd_make_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
cmd_make_empty_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)
quiet_cmd_link_o_target = AR $@
-# If the list of objects to link is empty, just create an empty built-in.o
+# If the list of objects to link is empty, just create an empty built-in.a
cmd_link_o_target = $(if $(strip $(obj-y)),\
$(cmd_make_builtin) $@ $(filter $(obj-y), $^) \
$(cmd_secanalysis),\
# Handle objects in subdirs
# ---------------------------------------------------------------------------
-# o if we encounter foo/ in $(obj-y), replace it by foo/built-in.o
+# o if we encounter foo/ in $(obj-y), replace it by foo/built-in.a
# and add the directory to the list of dirs to descend into: $(subdir-y)
# o if we encounter foo/ in $(obj-m), remove it from $(obj-m)
# and add the directory to the list of dirs to descend into: $(subdir-m)
subdir-y += $(__subdir-y)
__subdir-m := $(patsubst %/,%,$(filter %/, $(obj-m)))
subdir-m += $(__subdir-m)
-obj-y := $(patsubst %/, %/built-in.o, $(obj-y))
+obj-y := $(patsubst %/, %/built-in.a, $(obj-y))
obj-m := $(filter-out %/, $(obj-m))
# Subdirectories we need to descend into
# $(subdir-obj-y) is the list of objects in $(obj-y) which uses dir/ to
# tell kbuild to descend
-subdir-obj-y := $(filter %/built-in.o, $(obj-y))
+subdir-obj-y := $(filter %/built-in.a, $(obj-y))
# $(obj-dirs) is a list of directories that contain object files
obj-dirs := $(dir $(multi-objs) $(obj-y))
# link vmlinux
#
# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
-# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
+# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
# from top-level directories in the kernel tree, others are specified in
# arch/$(ARCH)/Makefile. Ordering when linking is important, and
# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
# | +--< init/version.o + more
# |
# +--< $(KBUILD_VMLINUX_MAIN)
-# | +--< drivers/built-in.o mm/built-in.o + more
+# | +--< drivers/built-in.a mm/built-in.a + more
# |
# +--< $(KBUILD_VMLINUX_LIBS)
# | +--< lib/lib.a + more
#
# Traditional incremental style of link does not require this step
#
-# built-in.o output file
+# built-in.a output file
#
archive_builtin()
{
- info AR built-in.o
- rm -f built-in.o;
- ${AR} rcsTP${KBUILD_ARFLAGS} built-in.o \
+ info AR built-in.a
+ rm -f built-in.a;
+ ${AR} rcsTP${KBUILD_ARFLAGS} built-in.a \
${KBUILD_VMLINUX_INIT} \
${KBUILD_VMLINUX_MAIN}
}
local objects
objects="--whole-archive \
- built-in.o \
+ built-in.a \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
- built-in.o \
+ built-in.a \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
- built-in.o \
+ built-in.a \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
rm -f .tmp_kallsyms*
rm -f .tmp_version
rm -f .tmp_vmlinux*
- rm -f built-in.o
+ rm -f built-in.a
rm -f System.map
rm -f vmlinux
rm -f vmlinux.o
s:^\./::;
if (/.*\.o$/ &&
! (
- m:/built-in.o$:
+ m:/built-in.a$:
|| m:arch/x86/vdso/:
|| m:arch/x86/boot/:
|| m:arch/ia64/ia32/ia32.o$:
ld -m elf_i386 --format binary --oformat elf32-i386 -r \
-T initramfs_data.scr initramfs_data.cpio.gz -o initramfs_data.o
- ld -m elf_i386 -r -o built-in.o initramfs_data.o
+ ld -m elf_i386 -r -o built-in.a initramfs_data.o
For including the .init.ramfs sections, see include/asm-generic/vmlinux.lds.
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