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 should be correct for a rootfs too, because: |
- | + | ''Dump of /proc/mtd from N800 running diablo'' | |
+ | <pre> | ||
+ | dev: size erasesize name | ||
+ | ... | ||
+ | mtd3: 00400000 00020000 "initfs" | ||
+ | mtd4: 0f980000 00020000 "rootfs" | ||
+ | </pre> | ||
- | + | As you can see, the erase size number for the rootfs and initfs is the same. Don't get put off by the 00020000 number either, 128 is the '''correct''' number for the -e mkfs.jffs2 argument. | |
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== Installing on the tablet == | == Installing on the tablet == | ||
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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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