Editing Modifying the root image
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- | This article describes two methods for extending and modifying an existing tablet JFFS2 root image | + | This article describes two methods for extending and modifying an existing tablet JFFS2 root image. |
== Background == | == Background == | ||
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== Repacking the image == | == Repacking the image == | ||
- | [http://maemo.org/development/documentation/ | + | [http://maemo.org/development/documentation/how-tos/2-x/howto_use_flasher_rootfs.html Using the flasher utility and creating the reference root file system] |
== Modifying the copy of the image == | == Modifying the copy of the image == | ||
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:<pre> sudo mkfs.jffs2 -r myRootImage -o myRootImage.jffs2 -e 128 -l -n </pre> | :<pre> sudo mkfs.jffs2 -r myRootImage -o myRootImage.jffs2 -e 128 -l -n </pre> | ||
- | Where ''myRootImage'' is the root of your new filesystem and ''myRootImage.jffs2'' is the name of the output file. -e 128 specifies a erase size of | + | Where ''myRootImage'' is the root of your new filesystem and ''myRootImage.jffs2'' is the name of the output file. -e 128 specifies a erase size of 128KiB. 128KiB is the correct erase size for the initfs. It is correct for an rootfs too. |
== Making the jffs2 image mount faster == | == Making the jffs2 image mount faster == | ||
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== Shell script to mount/unmount JFFS2 using block device emulating MTD == | == Shell script to mount/unmount JFFS2 using block device emulating MTD == | ||
Create a shell script (mount_jffs2.sh) from the following: | Create a shell script (mount_jffs2.sh) from the following: | ||
- | < | + | <pre> |
- | #!/bin/sh | + | #!/bin/sh |
- | JFFSIMG=$1 # jffs image | + | JFFSIMG=$1 # jffs image |
- | LOOP="/dev/loop1" # loop device | + | LOOP="/dev/loop1" # loop device |
- | MP="/media/jffs2" # mount point | + | MP="/media/jffs2" # mount point |
- | MTDBLOCK="/tmp/mtdblock0" # MTD device file | + | MTDBLOCK="/tmp/mtdblock0" # MTD device file |
- | KVER="2.6" | + | KVER="2.6" |
- | BLKMTD="block2mtd" | + | BLKMTD="block2mtd" |
- | UMNT="" | + | UMNT="" |
- | echo "$0" | grep unmount_ >/dev/null 2>&1 | + | echo "$0" | grep unmount_ >/dev/null 2>&1 |
- | [ $? -eq 0 ] && UMNT=1 | + | [ $? -eq 0 ] && UMNT=1 |
- | if [ $# -gt 1 -a x"$2"x = x"unmount"x ]; then | + | if [ $# -gt 1 -a x"$2"x = x"unmount"x ]; then |
- | + | UMNT=1 | |
- | fi | + | fi |
- | uname -r | egrep '^2\.6' >/dev/null 2>&1 | + | uname -r | egrep '^2\.6' >/dev/null 2>&1 |
- | if [ $? -ne 0 ]; then | + | if [ $? -ne 0 ]; then |
- | + | KVER="2.4" | |
- | + | BLKMTD=blkmtd | |
- | fi | + | fi |
- | if [ x"${UMNT}"x = x""x ]; then | + | if [ x"${UMNT}"x = x""x ]; then |
- | + | if [ ! -b ${MTDBLOCK} ] ; then | |
- | + | mknod ${MTDBLOCK} b 31 0 || exit 1 | |
- | + | fi | |
- | + | lsmod | grep loop >/dev/null 2>&1 | |
- | + | if [ $? -ne 0 [; then | |
- | + | modprobe loop | |
- | + | [ $? -ne 0 ] && echo "loopback loading failed" && exit 1 | |
- | + | sleep 1 | |
- | + | fi | |
- | + | losetup ${LOOP} ${JFFSIMG} || exit 1 | |
- | + | sleep 1 | |
- | + | modprobe mtdblock | |
- | + | if [ x"${KVER}"x = x"2.4"x [; then | |
- | + | modprobe ${BLKMTD} device=${LOOP} || exit 1 | |
- | + | else | |
- | + | modprobe ${BLKMTD} || exit 1 | |
- | + | echo "${LOOP}" > /sys/module/block2mtd/parameters/block2mtd | |
- | + | fi | |
- | + | sleep 1 | |
- | + | modprobe jffs2 | |
- | + | [ ! -d ${MP} ] && mkdir -p ${MP} | |
- | + | mount -t jffs2 ${MTDBLOCK} ${MP} || exit 1 | |
- | else | + | else |
- | + | umount ${MP} | |
- | + | if [ $? -ne 0 ]; then | |
- | + | echo "Cannot unmount JFFS2 at $MP" && exit 1 | |
- | + | fi | |
- | + | modprobe -r jffs2 | |
- | + | modprobe -r ${BLKMTD} | |
- | + | modprobe -r mtdblock | |
- | + | sleep 1 | |
- | + | losetup -d ${LOOP} | |
- | fi | + | fi |
- | </ | + | </pre> |
Make sure you chmod a+x mount_jffs2.sh to make the shell script executable. | Make sure you chmod a+x mount_jffs2.sh to make the shell script executable. | ||
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== Shell script to mount/unmount JFFS2 using kernel memory emulating MTD == | == Shell script to mount/unmount JFFS2 using kernel memory emulating MTD == | ||
Create a shell script (mount_jffs2.sh) from the following: | Create a shell script (mount_jffs2.sh) from the following: | ||
- | < | + | <pre> |
- | #!/bin/sh | + | #!/bin/sh |
- | JFFSIMG=$1 # jffs image | + | JFFSIMG=$1 # jffs image |
- | MP="/media/jffs2" # mount point | + | MP="/media/jffs2" # mount point |
- | MTDBLOCK="/tmp/mtdblock0" # MTD device file | + | MTDBLOCK="/tmp/mtdblock0" # MTD device file |
- | UMNT="" | + | UMNT="" |
- | echo "$0" | grep unmount_ >/dev/null 2>&1 | + | echo "$0" | grep unmount_ >/dev/null 2>&1 |
- | [ $? -eq 0 ] && UMNT=1 | + | [ $? -eq 0 ] && UMNT=1 |
- | if [ $# -gt 1 -a x"$2"x = x"unmount"x ]; then | + | if [ $# -gt 1 -a x"$2"x = x"unmount"x ]; then |
- | + | UMNT=1 | |
- | fi | + | fi |
- | if [ x"${UMNT}"x = x""x ]; then | + | if [ x"${UMNT}"x = x""x ]; then |
- | + | if [ ! -b ${MTDBLOCK} ] ; then | |
- | + | mknod ${MTDBLOCK} b 31 0 || exit 1 | |
- | + | fi | |
- | + | modprobe mtdblock | |
- | + | modprobe mtdram total_size=65536 erase_size=256 | |
- | + | modprobe jffs2 | |
- | + | dd if=${JFFSIMG} of=${MTDBLOCK} | |
- | + | [ ! -d ${MP} ] && mkdir -p ${MP} | |
- | + | mount -t jffs2 ${MTDBLOCK} ${MP} | |
- | else | + | else |
- | + | umount ${MP} | |
- | + | if [ $? -ne 0 ]; then | |
- | + | echo "Cannot unmount JFFS2 at $MP" && exit 1 | |
- | + | fi | |
- | + | modprobe -r jffs2 | |
- | + | modprobe -r mtdram | |
- | + | modprobe -r mtdblock | |
- | fi | + | fi |
- | </ | + | </pre> |
Make sure you chmod a+x mount_jffs2.sh to make the shell script executable. | Make sure you chmod a+x mount_jffs2.sh to make the shell script executable. | ||
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./mount_jffs2.sh rootfs.jffs2 unmount | ./mount_jffs2.sh rootfs.jffs2 unmount | ||
- | [[Category: | + | |
+ | [[Category:HowTos]] | ||
[[Category:Wiki page of the day]] | [[Category:Wiki page of the day]] |
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