Creating an Initramfs - Revision history

Michael.six at 05:55, 31 October 2009

2009-10-31T05:55:15Z

← Older revision		Revision as of 22:55, 30 October 2009
Line 133:		Line 133:
	cat ${module} > /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}/$(basename ${module})		cat ${module} > /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}/$(basename ${module})
	;;		;;
	*.ko.gz)		*.ko.gz)
	gzip -dc ${module} > /boot/initramfs-tree/lib/modules${initramfs_use_kernel}/$(basename ${module} .gz)		gzip -dc ${module} > /boot/initramfs-tree/lib/modules${initramfs_use_kernel}/$(basename ${module} .gz)
	:;		:;

Michael.six at 05:53, 31 October 2009

2009-10-31T05:53:20Z

← Older revision		Revision as of 22:53, 30 October 2009
Line 49:		Line 49:
	usage(){		usage(){
	cat << EOT		cat << EOT
	$(basename ${0}) -c -k 2.6.30.2 -m ext3 -r /dev/hda3 -~~f ext3~~		$(basename ${0}) -c -k 2.6.30.2 -m ext3 -r /dev/hda3 -o /boot/initramfs.igz-2.6.30.2
	EOT		EOT
	}		}

Michael.six at 05:51, 31 October 2009

2009-10-31T05:51:50Z

← Older revision		Revision as of 22:51, 30 October 2009
Line 1:		Line 1:
	{{Package-Introduction\|The mkinitramfs script creates a gzip compressed cpio archive using busybox and a simple shell init script, which can be used in place of an initrd to do such things as load kernel modules before the system boots, in order to access functionality that is not compiled into the kernel, and therefore must be loaded, such as usb disks, scsi disks, etc. This is different than loading modules automatically at boot time, because those are loaded after the root disk is mounted, fsck'd etc, and typically an initrd contains modules which are loaded into the kernel before anything else, to fascilitate mounting the root fs. IE kernel doesn't have reiserfs support compiled in, but your root fs is formatted reiserfs}}		{{Package-Introduction\|The mkinitramfs script creates a gzip compressed cpio archive using busybox and a simple shell init script, which can be used in place of an initrd to do such things as load kernel modules before the system boots, in order to access functionality that is not compiled into the kernel, and therefore must be loaded, such as usb disks, scsi disks, etc. This is different than loading modules automatically at boot time, because those are loaded after the root disk is mounted, fsck'd etc, and typically an initrd contains modules which are loaded into the kernel before anything else, to fascilitate mounting the root fs. IE kernel doesn't have reiserfs support compiled in, but your root disk is formatted reiserfs}}
	== Dependencies ==		== Dependencies ==

Michael.six at 05:50, 31 October 2009

2009-10-31T05:50:19Z

← Older revision		Revision as of 22:50, 30 October 2009
Line 27:		Line 27:
	which can act as an initrd.		which can act as an initrd.

	-c - remove initramfs-tree before creating the		-c - remove initramfs-tree before creating the
	initramfs		initramfs

	-v\|--verbose - use verbose messages		-v\|--verbose - use verbose messages

	-k <version> - use modules from kernel <version>		-k <version> - use modules from kernel <version>

	-m <arg1,arg2> - comma separated list of additional modules		-m <arg1,arg2> - comma separated list of additional modules
	besides the ones contained in the file		besides the ones contained in the file
	/etc/sysconfig/mkinitramfs.modules to add		/etc/sysconfig/mkinitramfs.modules to add
	to the initramfs archive		to the initramfs archive

	-o <arg> - output finished archive to <arg> instead		-o <arg> - output finished archive to <arg> instead
	of /boot/initramfs.igz		of /boot/initramfs.igz

	-r\|--rootfs - use device as ~~root device~~		-r\|--rootfs - use device as root device

	~~-f\|--rootfstype - use filesystem type for~~ root device

	Example:		Example:
Line 97:		Line 95:
	-r\|--rootfs)		-r\|--rootfs)
	initramfs_use_rootfs="${2}"		initramfs_use_rootfs="${2}"
	~~shift~~
	;;
	~~-f\|--rootfstype)~~
	~~initramfs_use_rootfstype="${2}"~~
	shift		shift
	;;		;;
Line 125:		Line 119:
	if [ ! -d '/boot/initramfs-tree' ]; then		if [ ! -d '/boot/initramfs-tree' ]; then
	mkdir /boot/initramfs-tree		mkdir /boot/initramfs-tree
	mkdir /boot/initramfs-tree/{bin,sbin,lib,etc,proc}		mkdir /boot/initramfs-tree/{bin,sbin,lib,etc,proc,root,sys,mnt}
	mkdir /boot/initramfs-tree/{lib/modules~~,root,sys,mnt~~}		mkdir /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}
	ln -s . /boot/initramfs-tree/usr		ln -s . /boot/initramfs-tree/usr
	fi		fi
Line 137:		Line 131:
	case "${module}" in		case "${module}" in
	*.ko)		*.ko)
	cat ${module} > /boot/initramfs-tree/lib/modules/~~$(basename ${module})~~		cat ${module} > /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}/$(basename ${module})
	;;
	*.ko.gz)
	~~gzip -dc~~ ${~~module~~} ~~> /boot/initramfs-tree/lib/modules~~/$(basename ${module} ~~.gz~~)
	;;		;;
			*.ko.gz)
			gzip -dc ${module} > /boot/initramfs-tree/lib/modules${initramfs_use_kernel}/$(basename ${module} .gz)
			:;
	esac		esac
	else		else
Line 156:		Line 150:
	case "${module}" in		case "${module}" in
	*.ko)		*.ko)
	cat ${module} > /boot/initramfs-tree/lib/modules/$(basename ${module})		cat ${module} > /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}/$(basename ${module})
	echo "$(basename ${module} .ko)" >> /boot/initramfs-tree/etc/modules		echo "$(basename ${module} .ko)" >> /boot/initramfs-tree/etc/modules
	;;		;;
	*.ko.gz)		*.ko.gz)
	gzip -dc ${module} > /boot/initramfs-tree/lib/modules/$(basename ${module} .gz)		gzip -dc ${module} > /boot/initramfs-tree/lib/modules/${initramfs_use_kernel}/$(basename ${module} .gz)
	echo "$(basename ${module} .ko.gz)" >> /boot/initramfs-tree/etc/modules		echo "$(basename ${module} .ko.gz)" >> /boot/initramfs-tree/etc/modules
	;;		;;
Line 182:		Line 176:
	/bin/busybox clear		/bin/busybox clear
	/bin/busybox cat << END		/bin/busybox cat << END
	This system is uses Community Beyond Linux From Scratch		This system uses Community Beyond Linux From Scratch
	<http://cblfs.cross-lfs.org/>		<http://cblfs.cross-lfs.org/>
	END		END
Line 206:		Line 200:
	# would return "/sbin/init"		# would return "/sbin/init"
	get_opt() {		get_opt() {
	echo "\$@" \| /bin/busybox cut -d "=" -f 2		echo "\$@" \| /bin/busybox cut -d "=" -f 2
	}		}
	# Defaults		# Defaults
Line 226:		Line 220:
	done		done
	# Mount the root device		# Mount the root device
	mount -o ro ~~-t ${initramfs_use_rootfstype}~~ "\${root}" /root		mount -o ro "\${root}" /root
	if [ -f /root/lfs-root.img ]; then		# Below is an example of how to use the initramfs
	BNROOT=\$(/bin/busybox basename "\${root}")		# to load clfs or lfs from a disk image
	umount root		#if [ -f /root/lfs-root.img ]; then
	mkdir -p /mnt/"\${BNROOT}" &&		# BNROOT=\$(/bin/busybox basename "\${root}")
	mount "\${root}" /mnt/"\${BNROOT}" &&		# umount root
	mount -o loop /mnt/"\${BNROOT}"/lfs-root.img /root &&		# mkdir -p /mnt/"\${BNROOT}" &&
	mkdir -p /root/mnt/"\${BNROOT}" &&		# mount "\${root}" /mnt/"\${BNROOT}" &&
	mount /mnt/"\${BNROOT}" /root/mnt/"\${BNROOT}"		# mount -o loop /mnt/"\${BNROOT}"/lfs-root.img /root &&
	unset BNROOT		# mkdir -p /root/mnt/"\${BNROOT}" &&
	fi		# mount /mnt/"\${BNROOT}" /root/mnt/"\${BNROOT}"
	if [[ -x "/root/\${init}" ]]; then		# unset BNROOT
			#fi
			if [ -x "/root/\${init}" ]; then
	# Unmount all other mounts so that the ram used by		# Unmount all other mounts so that the ram used by
	# the initramfs can be cleared after switch_root		# the initramfs can be cleared after switch_root
Line 249:		Line 245:
	EOT		EOT
	chmod 755 /boot/initramfs-tree/init		chmod 755 /boot/initramfs-tree/init
			( cd /boot/initramfs-tree
			find . \| cpio -H newc -o \| gzip -9c > ${initramfs_output}
			) \|\| exit 1
	EOF		EOF
	chmod 755 /usr/sbin/mkinitramfs		chmod 755 /usr/sbin/mkinitramfs

Michael.six at 07:08, 30 October 2009

2009-10-30T07:08:04Z

Show changes

Michael.six at 06:45, 30 October 2009

2009-10-30T06:45:58Z

Show changes

Michael.six: I wrote this script myself compiled from various information I found by googling

2009-10-30T01:05:20Z

I wrote this script myself compiled from various information I found by googling

New page

{{Package-Introduction|The mkinitramfs script creates a gzip compressed cpio archive using busybox and a simple shell init script, which can be used in place of an initrd to do such things as load kernel modules before the system boots, in order to access functionality that is not compiled into the kernel, and therefore must be loaded, such as usb disks, scsi disks, etc. This is different than loading modules automatically at boot time, because those are loaded after the root disk is mounted, fsck'd etc, and typically an initrd contains modules which are loaded into the kernel before anything else, to fascilitate mounting the root fs. IE kernel doesn't have reiserfs support compiled in, but your root fs is formatted reiserfs}}
== Dependencies ==

=== Required ===
* [[Cpio]]
* [[Busybox]]

{{Note|The init script created for the initramfs will drop to the shell in busybox if there is an error, while only a few things are actually needed for the init to function, while compiling busybox you might want to keep in mind that it may need additional functionality to be able to work properly if the initramfs drops to the shell. Also this assumes that busybox is compiled statically linked, if that is not the case, additional libraries will be required to be added to the initramfs-tree. To test this run 'file /bin/busybox'. If file reports it as dynamically linked, running 'ldd /bin/busybox' should help you determine what libraries may be needed.}}

== Creating the mkinitramfs script ==

cat > /usr/sbin/mkinitramfs << "END"
#!/bin/bash
# This is a bash script to create a busybox
# based gzipped cpio archive to be used as
# an initrd
INITRAMFS_USE_KERNEL="$(uname -r)"
INITRAMFS_OUTPUT="/boot/initramfs.igz"
until [ -z "${1}" ]; do
case ${1} in
-c) rm -rf /boot/initramfs-tree
;;
-k)
INITRAMFS_USE_KERNEL="${2}"
shift
;;
-m)
INITRAMFS_USE_MODULES="${2}"
shift
;;
-v|--verbose)
INITRAMFS_USE_VERBOSE="true"
;;
-m)
INITRAMFS_USE_MODULES="${2}"
shift
;;
-o)
INITRAMFS_OUTPUT="${2}"
shift
;;
esac
shift
done
ermsg(){
cat << EOF
[ERROR] $@
EOF
}
killme(){
ermsg "$@"
ermsg "Exiting ..."
exit 1
}
vrbmsg(){
if [ "${INITRAMFS_USE_VERBOSE}" = 'true' ]; then
cat << EOF
$@
EOF
fi
}
if [ ! -x /bin/busybox ]; then
killme "The initramfs needs busybox ..."
fi
if [ ! -x /usr/bin/cpio ]; then
killme "The initramfs needs cpio ..."
fi
if [ ! -x /bin/gzip ]; then
killme "The initramfs needs gzip ..."
fi
rm -f /tmp/mkinitramfs.modules
rm -f /tmp/mkinitramfs.moddeps
get_moddeps(){
if [ -f /lib/modules/${INITRAMFS_USE_KERNEL}/modules.dep ]; then
grep "${1}": /lib/modules/${INITRAMFS_USE_KERNEL}/modules.dep \
| sed -e "s|${1}:||"
else
cat << EOF
get_moddeps failure
EOF
fi
}
fnd_module(){
fnd_mod_outpt="$(find /lib/modules/${INITRAMFS_USE_KERNEL} -name ${1}.ko)"
if [ -z "${fnd_mod_oupt}" ]; then
fnd_mod_outpt="$(find /lib/modules/${INITRAMFS_USE_KERNEL} -name ${1}.ko.gz)"
fi
echo ${fnd_mod_outpt} | sed -e "s|/lib/modules/${INITRAMFS_USE_KERNEL}/||"
}
if [ ! -d /boot/initramfs-tree ]; then
mkdir /boot/initramfs-tree &&
mkdir /boot/initramfs-tree/{etc,bin,sbin,lib} &&
mkdir /boot/initramfs-tree/{proc,root,mnt,sys}
mkdir /boot/initramfs-tree/lib/modules \
|| killme "Problem making the initramfs-tree ..."
ln -s . /boot/initramfs-tree/usr
fi
if [ -f /etc/sysconfig/initramfs.modules ]; then
cat /etc/sysconfig/initramfs.modules | while read line; do
if [ -n "${line}" -a "$(head -c1 <<<${line})" != "#" ]; then
if [ -n "$(fnd_module ${line})" ]; then
fnd_module ${line} >> /tmp/mkinitramfs.modules
else
ermsg "Couldn't find module ${line}"
fi
fi
done
fi
if [ -n "${INITRAMFS_USE_MODULES}" ]; then
for ITEM in $(echo ${INITRAMFS_USE_MODULES//,/ }); do
if [ -n "$(fnd_module ${ITEM})" ]; then
fnd_module ${ITEM} >> /tmp/mkinitramfs.modules
else
ermsg "Couldn't find module ${ITEM}"
fi
done
unset ITEM
fi
touch /tmp/mkinitramfs.moddeps
if [ -f /tmp/mkinitramfs.modules ]; then
cat /tmp/mkinitramfs.modules | while read IMOD; do
vrbmsg "generating module dependencies for ${IMOD}" &&
if [ "$(get_moddeps ${IMOD})" != "get_moddeps failure" ]; then
if [ -n "$(get_moddeps ${IMOD})" ]; then
for ITEM in $(get_moddeps ${IMOD}); do
if [ -z "$(grep ${IMOD} /tmp/mkinitramfs.moddeps)" ]; then
echo "${ITEM}" >> /tmp/mkinitramfs.moddeps
fi
done
unset ITEM
fi
fi
if [ -z "$(grep ${IMOD} /tmp/mkinitramfs.moddeps)" ]; then
echo "${IMOD}" >> /tmp/mkinitramfs.moddeps
fi
done
fi
unset IMOD
if [ -f /tmp/mkinitramfs.moddeps ]; then
cat /tmp/mkinitramfs.moddeps | while read line; do
case ${line} in
*.ko.gz)
gzip -dc /lib/modules/${INITRAMFS_USE_KERNEL}/${line} \
> /boot/initramfs-tree/lib/modules/$(basename ${line} .ko.gz).ko
echo "$(basename ${line} .ko.gz)" >> /boot/initramfs-tree/etc/modules
;;
*.ko)
cat /lib/modules/${MKINITRAMFS_USE_KERNEL}/${line} \
> /boot/initramfs-tree/lib/modules/$(basename ${line})
echo "$(basename ${line} .ko)" >> /boot/initramfs-tree/etc/modules
;;
esac
done
fi
# Now for the init
cat << "EOT" >/boot/initramfs-tree/init
#!/bin/busybox sh
# Mount things which are needed by this script
/bin/busybox mount -t proc proc /proc
/bin/busybox mount -t sysfs sysfs /sys
# Disable kernel messages from popping up on
# the screen
/bin/busybox echo 0 > /proc/sys/kernel/printk
# Clear the screen
/bin/busybox clear
/bin/busybox cat << EOF
This system is uses Community Beyond Linux From Scratch
<http://cblfs.cross-lfs.org/>
EOF
# Create the symlinks to busybox
/bin/busybox --install -s
# Create device nodes
/bin/busybox mknod /dev/null c 1 3
/bin/busybox mknod /dev/tty c 5 0
# Check for modules
if [ -f /etc/modules ]; then
/bin/busybox depmod /lib/modules
/bin/busybox cat /etc/modules | while read line; do
if [ -n "${line}" ]; then
/bin/busybox modprobe ${line/.ko/}
fi
done
fi
# Sleep for devices to connect, like USB
/bin/busybox sleep 5
/bin/busybox mdev -s
# Function for parsing command line options with
# '=' in them. Ex. get_opt("init=/sbin/init")
# would return "/sbin/init"
get_opt() {
echo "$@" | /bin/busybox cut -d "=" -f 2
}
# Defaults
init="/sbin/init"
root="/dev/hda1"
runlevel="3"
for i in $(cat /proc/cmdline); do
case ${i} in
root\=*)
root=$(get_opt ${i})
;;
init\=*)
init=$(get_opt ${i})
;;
runlevel\=*)
runlevel=$(get_opt ${i})
;;
esac
done
# Mount the root device
mount -o ro "${root}" /root
# Below is an example for loading a disk image from
# a linux partition
if [ -f /root/lfs-root.img ]; then
BNROOT=$(/bin/busybox basename "${root}")
umount root
mkdir -p /mnt/"${BNROOT}" &&
mount "${root}" /mnt/"${BNROOT}" &&
mount -o loop /mnt/"${BNROOT}"/lfs-root.img /root &&
# Make sure that we don't lose access to the partition
# containing the disk image
mkdir -p /root/mnt/"${BNROOT}" &&
mount /mnt/"${BNROOT}" /root/mnt/"${BNROOT}"
unset BNROOT
fi
# Check if the $init exists, and is executable
if [[ -x "/root/${init}" ]]; then
# Unmount all other mounts so that the ram used by
# the initramfs can be cleared after switch_root
umount /sys /proc

# Switch to the new root and execute the init at
# the specified runlevel
exec switch_root /root "${init}" "${runlevel}"
fi

# This will only be run if the exec above failed
echo "Failed 'exec switch_root /root \"${init}\" \"${runlevel}\"'"
exec sh
EOT
chmod 0755 /boot/initramfs-tree/init
cat /bin/busybox > /boot/initramfs-tree/bin/busybox
chmod 0755 /boot/initramfs-tree/bin/busybox
if [ ! -d "$(dirname ${INITRAMFS_OUTPUT})" ]; then
killme "Cannot create ${INITRAMFS_OUTPUT}"
fi
( cd /boot/initramfs-tree &&
find . | cpio -H newc -o | gzip -9c > ${INITRAMFS_OUTPUT} || exit 1
) || exit 1
rm -f /tmp/mkinitramfs.modules
rm -f /tmp/mkinitramfs.moddeps
unset INITRAMFS_OUTPUT INITRAMFS_USE_KERNEL INITRAMFS_USE_MODULES INITRAMFS_USE_KERNEL
END
chmod 0755 /usr/sbin/mkinitramfs