Modifying the root image - Revision history

121.217.111.231: /* Block device emulating an MTD device */

2019-06-16T07:57:45Z

Block device emulating an MTD device

← Older revision		Revision as of 07:57, 16 June 2019
Line 58:		Line 58:

	Or use the [[#Shell_script_to_mount/unmount_JFFS2_using_block_device_emulating_MTD\|automated shell script]].		Or use the [[#Shell_script_to_mount/unmount_JFFS2_using_block_device_emulating_MTD\|automated shell script]].

			---

			Edit in 2019 - Hi. I (i336_) thought I'd leave the eraseblock size off since I'm on kernel 5.1.4.

			My HDD promptly began seeking a lot for a few seconds (!), and I discovered this was because it was scrambling to keep up with the just-over-30,000 errors jffs had just dumped into syslog.

			You definitely still need the ",128KiB". :)

	=== Kernel memory emulating an MTD device ===		=== Kernel memory emulating an MTD device ===

imported_>amigadave: wikify slightly

2011-02-09T15:46:07Z

wikify slightly

Show changes

imported_>pelago: Added N900 link (should be copied into the page really)

2010-03-13T23:34:40Z

Added N900 link (should be copied into the page really)

← Older revision		Revision as of 23:34, 13 March 2010
Line 1:		Line 1:
	This article describes two methods for extending and modifying an existing tablet JFFS2 root image. Note that this article does not work with the "root.jffs2" file for the N900, as despite the filename, the N900 does not use jffs2.		This article describes two methods for extending and modifying an existing tablet JFFS2 root image. Note that this article does not work with the "root.jffs2" file for the N900, as despite the filename, the N900 does not use jffs2. See http://talk.maemo.org/showpost.php?p=403015&postcount=3 for a solution for N900.

	== Background ==		== Background ==

imported_>pelago: d

2010-03-13T23:29:24Z

← Older revision		Revision as of 23:29, 13 March 2010
Line 1:		Line 1:
	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. Note that this article does not work with the "root.jffs2" file for the N900, as despite the filename, the N900 does not use jffs2.

	== Background ==		== Background ==

imported_>pelago: /* Shell script to mount/unmount JFFS2 using block device emulating MTD */ Fix brackets

2010-03-13T23:17:24Z

Shell script to mount/unmount JFFS2 using block device emulating MTD: Fix brackets

← Older revision		Revision as of 23:17, 13 March 2010
Line 163:		Line 163:
	fi		fi
	lsmod \| grep loop >/dev/null 2>&1		lsmod \| grep loop >/dev/null 2>&1
	if [ $? -ne 0 [; then		if [ $? -ne 0 ]; then
	modprobe loop		modprobe loop
	[ $? -ne 0 ] && echo "loopback loading failed" && exit 1		[ $? -ne 0 ] && echo "loopback loading failed" && exit 1
Line 171:		Line 171:
	sleep 1		sleep 1
	modprobe mtdblock		modprobe mtdblock
	if [ x"${KVER}"x = x"2.4"x [; then		if [ x"${KVER}"x = x"2.4"x ]; then
	modprobe ${BLKMTD} device=${LOOP} \|\| exit 1		modprobe ${BLKMTD} device=${LOOP} \|\| exit 1
	else		else

212.61.137.19: Fixed link

2009-12-09T10:15:50Z

Fixed link

← Older revision		Revision as of 10:15, 9 December 2009
Line 95:		Line 95:

	== Repacking the image ==		== Repacking the image ==
	[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]		[http://maemo.org/development/documentation/manuals/2-x/howto_use_flasher_rootfs/ Using the flasher utility and creating the reference root file system]

	== Modifying the copy of the image ==		== Modifying the copy of the image ==

imported_>twaelti at 21:07, 19 October 2009

2009-10-19T21:07:18Z

← Older revision		Revision as of 21:07, 19 October 2009
Line 246:		Line 246:


	[[Category:~~HowTos~~]]		[[Category:HowTo]]
	[[Category:Wiki page of the day]]		[[Category:Wiki page of the day]]

imported_>qwerty12: Added sumtool section.

2008-11-18T18:41:47Z

Added sumtool section.

← Older revision		Revision as of 18:41, 18 November 2008
Line 117:		Line 117:
	:<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 128KiB. 128KiB is the correct erase size for the initfs. It ~~should be~~ correct for a rootfs too~~, because:~~		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.

	~~''Dump of /proc/mtd from N800 running diablo''~~		== Making the jffs2 image mount faster ==
	~~<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.~~		The jffs2 image that was just created is a plain jffs2 image. That's nice and if you were to flash it, it would work fine but what you can do is use sumtool which makes an summarized JFFS2 image. An summarized JFFS2 image mounts faster than a non-summarized one.

			This can be done simply with:

			sumtool -i <input jffs2 image> -o <output jffs2 image> -e 128KiB -l -n

	== Installing on the tablet ==		== Installing on the tablet ==

78.86.35.231: /* Kernel memory emulating an MTD device */

2008-11-15T16:08:53Z

Kernel memory emulating an MTD device

← Older revision		Revision as of 16:08, 15 November 2008
Line 62:		Line 62:

	Note that mtdram requires 88mb of raw ram on a 2gb system to mount a ~2Mb initfs image [Faheem Pervez on -dev ml], it probably won't work well with a rootfs!		Note that mtdram requires 88mb of raw ram on a 2gb system to mount a ~2Mb initfs image [Faheem Pervez on -dev ml], it probably won't work well with a rootfs!

			Use total_size=85892 for mtdram if 65536 is too little.

	However, if you insist... to mount the JFFS2 image, you perform the following steps:		However, if you insist... to mount the JFFS2 image, you perform the following steps:

imported_>qwerty12: /* Making the actual jffs2 image */

2008-10-28T08:15:17Z

Making the actual jffs2 image

← Older revision		Revision as of 08:15, 28 October 2008
Line 108:		Line 108:
	== Making the actual jffs2 image ==		== Making the actual jffs2 image ==

	''This was done on a Ubuntu Hardy system and was only done to make an initfs image successfully. I can't ensure this will work for creating an ~~initfs~~.''		''This was done on a Ubuntu Hardy system and was only done to make an initfs image successfully. I can't ensure this will work (though in theory, it should do) for creating an rootfs.''

	<ol><li>Install mtd-tools which contains the required mkfs.jffs2.</li></ol>		<ol><li>Install mtd-tools which contains the required mkfs.jffs2.</li></ol>
	:<pre> sudo apt-get install mtd-tools </pre>		:<pre> sudo apt-get install mtd-tools </pre>
	<ol start="2"><li>Run:</li></ol>		<ol start="2"><li>Run:</li></ol>
	:<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 128KiB. 128KiB is the correct erase size for the initfs. It should be correct for a rootfs too, because:		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: