b1992c3772
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2.7 KiB
SPDX-License-Identifier: GPL-2.0
kbuild file for usr/ - including initramfs image
compress-y := copy compress-$(CONFIG_INITRAMFS_COMPRESSION_GZIP) := gzip compress-$(CONFIG_INITRAMFS_COMPRESSION_BZIP2) := bzip2 compress-$(CONFIG_INITRAMFS_COMPRESSION_LZMA) := lzma compress-$(CONFIG_INITRAMFS_COMPRESSION_XZ) := xzmisc compress-$(CONFIG_INITRAMFS_COMPRESSION_LZO) := lzo compress-$(CONFIG_INITRAMFS_COMPRESSION_LZ4) := lz4 compress-$(CONFIG_INITRAMFS_COMPRESSION_ZSTD) := zstd
obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o
$(obj)/initramfs_data.o: $(obj)/initramfs_inc_data
ramfs-input := $(CONFIG_INITRAMFS_SOURCE) cpio-data :=
If CONFIG_INITRAMFS_SOURCE is empty, generate a small initramfs with the
default contents.
ifeq ($(ramfs-input),) ramfs-input := $(src)/default_cpio_list endif
ifeq ($(words $(ramfs-input)),1)
If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
.cpio, use it directly as an initramfs.
ifneq ($(filter %.cpio,$(ramfs-input)),) cpio-data := $(ramfs-input) endif
If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
.cpio.*, use it directly as an initramfs, and avoid double compression.
ifeq ($(words $(subst .cpio.,$(space),$(ramfs-input))),2) cpio-data := $(ramfs-input) compress-y := copy endif
endif
For other cases, generate the initramfs cpio archive based on the contents
specified by CONFIG_INITRAMFS_SOURCE.
ifeq ($(cpio-data),)
cpio-data := $(obj)/initramfs_data.cpio
hostprogs := gen_init_cpio
.initramfs_data.cpio.d is used to identify all files included
in initramfs and to detect if any files are added/removed.
Removed files are identified by directory timestamp being updated
The dependency list is generated by gen_initramfs.sh -l
-include $(obj)/.initramfs_data.cpio.d
do not try to update files included in initramfs
$(deps_initramfs): ;
quiet_cmd_initfs = GEN $@
cmd_initfs =
$(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d
$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID))
$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID))
$(if $(KBUILD_BUILD_TIMESTAMP), -d "$(KBUILD_BUILD_TIMESTAMP)")
$(ramfs-input)
We rebuild initramfs_data.cpio if:
1) Any included file is newer than initramfs_data.cpio
2) There are changes in which files are included (added or deleted)
3) If gen_init_cpio are newer than initramfs_data.cpio
4) Arguments to gen_initramfs.sh changes
$(obj)/initramfs_data.cpio: $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_initramfs) FORCE $(call if_changed,initfs)
endif
$(obj)/initramfs_inc_data: $(cpio-data) FORCE $(call if_changed,$(compress-y))
targets += initramfs_data.cpio initramfs_inc_data
subdir-$(CONFIG_UAPI_HEADER_TEST) += include