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The file init/initramfs.c is always compiled and linked in the kernel vmlinux even when BLK_DEV_RAM and BLK_DEV_INITRD are disabled and the system isn't using any form of an initramfs or initrd. In this situation the code is only used to unpack a (static) default initial rootfilesystem. The current init/initramfs.c code. usr/initramfs_data.o compiles to a size of ~15 kbytes. Disabling BLK_DEV_RAM and BLK_DEV_INTRD shrinks the kernel code size with ~60 Kbytes. This patch avoids compiling in the code and data for initramfs support if CONFIG_BLK_DEV_INITRD is not defined. Instead of the initramfs code and data it uses a small routine in init/noinitramfs.c to setup an initial static default environment for mounting a rootfilesystem later on in the kernel initialisation process. The new code is: 164 bytes of size. The patch is separated in two parts: 1) doesn't compile initramfs code when CONFIG_BLK_DEV_INITRD is not set 2) changing all plaforms vmlinux.lds.S files to not reserve an area of PAGE_SIZE when CONFIG_BLK_DEV_INITRD is not set. [deweerdt@free.fr: warning fix] Signed-off-by: Jean-Paul Saman <jean-paul.saman@nxp.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
53 lines
1.8 KiB
Makefile
53 lines
1.8 KiB
Makefile
#
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# kbuild file for usr/ - including initramfs image
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#
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klibcdirs:;
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PHONY += klibcdirs
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# Generate builtin.o based on initramfs_data.o
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obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o
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# initramfs_data.o contains the initramfs_data.cpio.gz image.
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# The image is included using .incbin, a dependency which is not
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# tracked automatically.
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$(obj)/initramfs_data.o: $(obj)/initramfs_data.cpio.gz FORCE
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#####
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# Generate the initramfs cpio archive
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hostprogs-y := gen_init_cpio
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initramfs := $(CONFIG_SHELL) $(srctree)/scripts/gen_initramfs_list.sh
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ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)), \
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$(shell echo $(CONFIG_INITRAMFS_SOURCE)),-d)
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ramfs-args := \
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$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
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$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID))
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# .initramfs_data.cpio.gz.d is used to identify all files included
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# in initramfs and to detect if any files are added/removed.
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# Removed files are identified by directory timestamp being updated
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# The dependency list is generated by gen_initramfs.sh -l
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ifneq ($(wildcard $(obj)/.initramfs_data.cpio.gz.d),)
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include $(obj)/.initramfs_data.cpio.gz.d
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endif
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quiet_cmd_initfs = GEN $@
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cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)
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targets := initramfs_data.cpio.gz
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# do not try to update files included in initramfs
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$(deps_initramfs): ;
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$(deps_initramfs): klibcdirs
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# We rebuild initramfs_data.cpio.gz if:
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# 1) Any included file is newer then initramfs_data.cpio.gz
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# 2) There are changes in which files are included (added or deleted)
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# 3) If gen_init_cpio are newer than initramfs_data.cpio.gz
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# 4) arguments to gen_initramfs.sh changes
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$(obj)/initramfs_data.cpio.gz: $(obj)/gen_init_cpio $(deps_initramfs) klibcdirs
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$(Q)$(initramfs) -l $(ramfs-input) > $(obj)/.initramfs_data.cpio.gz.d
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$(call if_changed,initfs)
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