87f4900826
Dracut is the tool used by desktop distributions to build initrds. In the embedded world, it can be very useful, too, for instance when wanting to create an initramfs for a system recovery mode. Whereas it is definitively possible to achieve this with buildroot, the process is to have a dedicated buildroot configuration for that, and perform a full build. Instead of doing that, dracut can pick the needed binaries/shared libraries, configuration files, or kernel modules from the 'target' directory. The advantage is to save build time, and also to have a consistency between the packages versions taken for the recovery and the production filesystem. The principle of dracut is based on the so-called 'dracut modules'. The modules determine what will be included in the initramfs. For example, one of dracut's modules checks the kernel modules that are included and also includes the corresponding firmware blobs. On the host, they are on host/lib/dracut/modules.d Each directory as a prefix number for the order of execution, and at least a "module-setup.sh" script. Dracut sources all of them, and typically calls the "check()" function, which is the placeholder for required binaries (that are aimed to be polulated in the initrd), then the "depends()" function, that lists other modules to depend on, and the "install()" function, that makes the actual work. Dracut was initially thought to work with systems using systemd, but it can also work without it. Do to so, every "systemd-xxx" module must be disabled in the dracut configuration file. For convenience, the 05busybox-init module is provided, to support busybox init system. Note that this module should *not* be enabled when using systemd init. It is therefore only installed if busybox init is selected. Musl and uClibc make assumptions about the existence of some symlinks that are not discoverable with readelf. Therefore, another module 05libc-links is provided that creates those links. The module is installed regardless of which libc is used - the script itself discovers if the links need to be installed based on which libc is found. Signed-off-by: Thierry Bultel <thierry.bultel@linatsea.fr> [arnout@mind.be: many changes] Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Cc: Adam Duskett <aduskett@gmail.com> [yann.morin.1998@free.fr: some additional fixups] Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
49 lines
1.9 KiB
Makefile
49 lines
1.9 KiB
Makefile
################################################################################
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#
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# dracut
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#
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################################################################################
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DRACUT_VERSION = 055
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DRACUT_SOURCE = dracut-$(DRACUT_VERSION).tar.xz
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DRACUT_SITE = $(BR2_KERNEL_MIRROR)/linux/utils/boot/dracut
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DRACUT_LICENSE = GPL-2.0
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DRACUT_LICENSE_FILES = COPYING
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HOST_DRACUT_DEPENDENCIES = host-pkgconf host-kmod host-prelink-cross
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define HOST_DRACUT_POST_INSTALL_WRAPPER_SCRIPT
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mv $(HOST_DIR)/bin/dracut $(HOST_DIR)/bin/dracut.real
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install -D -m 0755 $(HOST_DRACUT_PKGDIR)/dracut_wrapper \
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$(HOST_DIR)/bin/dracut
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endef
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HOST_DRACUT_POST_INSTALL_HOOKS += HOST_DRACUT_POST_INSTALL_WRAPPER_SCRIPT
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# When using uClibc or musl, there must be "ld-uClibc.so.1" or
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# "ld-musl-x.so" symlinks, respectively - else the init process cannot
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# start
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define HOST_DRACUT_POST_INSTALL_LIBC_LINKS_MODULE
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$(INSTALL) -D -m 0755 package/dracut/libc-links-module-setup.sh \
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$(HOST_DIR)/lib/dracut/modules.d/05libc-links/module-setup.sh
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endef
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HOST_DRACUT_POST_INSTALL_HOOKS += HOST_DRACUT_POST_INSTALL_LIBC_LINKS_MODULE
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ifeq ($(BR2_INIT_BUSYBOX),y)
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# Dracut does not support busybox init (systemd init is assumed to work
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# out of the box, though). It provides a busybox module, that does not
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# use the same paths as buildroot, and is not meant to be used as an init
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# system.
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# So it is simpler for users to disable the standard 'busybox' module in
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# the configuration file, and enable the "busybox-init' module instead.
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# Note that setting the script as executable (0755) is not mandatory,
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# but this is what dracut does on all its modules, so lets just conform
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# to it.
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define HOST_DRACUT_POST_INSTALL_BUSYBOX_INIT_MODULE
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$(INSTALL) -D -m 0755 package/dracut/busybox-init-module-setup.sh \
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$(HOST_DIR)/lib/dracut/modules.d/05busybox-init/module-setup.sh
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endef
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HOST_DRACUT_POST_INSTALL_HOOKS += HOST_DRACUT_POST_INSTALL_BUSYBOX_INIT_MODULE
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endif
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$(eval $(host-autotools-package))
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