Provided by: mtd-utils_2.1.1-1ubuntu1_amd64 
NAME
mkfs.jffs2 - Create a JFFS2 file system image from directory
SYNOPSIS
mkfs.jffs2 [ -p,--pad[=SIZE] ] [ -r,-d,--root directory ] [ -s,--pagesize=SIZE ] [ -e,--eraseblock=SIZE ]
[ -c,--cleanmarker=SIZE ] [ -n,--no-cleanmarkers ] [ -o,--output image.jffs2 ] [ -l,--little-endian ] [
-b,--big-endian ] [ -D,--devtable=FILE ] [ -f,--faketime ] [ -q,--squash ] [ -U,--squash-uids ] [
-P,--squash-perms ] [ --with-xattr ] [ --with-selinux ] [ --with-posix-acl ] [ -m,--compression-mode=MODE
] [ -x,--disable-compressor=NAME ] [ -X,--enable-compressor=NAME ] [ -y,--compressor-
priority=PRIORITY:NAME ] [ -L,--list-compressors ] [ -t,--test-compression ] [ -h,--help ] [ -v,--verbose
] [ -V,--version ] [ -i,--incremental image.jffs2 ]
DESCRIPTION
The program mkfs.jffs2 creates a JFFS2 (Second Journalling Flash File System) file system image and
writes the resulting image to the file specified by the -o option or by default to the standard output,
unless the standard output is a terminal device in which case mkfs.jffs2 will abort.
The file system image is created using the files and directories contained in the directory specified by
the option -r or the present directory, if the -r option is not specified.
Each block of the files to be placed into the file system image are compressed using one of the available
compressors depending on the selected compression mode.
File systems are created with the same endianness as the host, unless the -b or -l options are specified.
JFFS2 driver in the 2.4 Linux kernel only supported images having the same endianness as the CPU. As of
2.5.48, the kernel can be changed with a #define to accept images of the non-native endianness. Full bi-
endian support in the kernel is not planned.
It is unlikely that JFFS2 images are useful except in conjuction with the MTD (Memory Technology Device)
drivers in the Linux kernel, since the JFFS2 file system driver in the kernel requires MTD devices.
OPTIONS
Options that take SIZE arguments can be specified as either decimal (e.g., 65536), octal (0200000), or
hexidecimal (0x1000).
-p, --pad[=SIZE]
Pad output to SIZE bytes with 0xFF. If SIZE is not specified, the output is padded to the end of
the final erase block.
-r, -d, --root=DIR
Build file system from directory DIR. The default is the current directory.
-s, --pagesize=SIZE
Use page size SIZE. The default is 4 KiB. This size is the maximum size of a data node. Set
according to target system's memory management page size (NOTE: this is NOT related to NAND page
size).
-e, --eraseblock=SIZE
Use erase block size SIZE. The default is 64 KiB. If you use a erase block size different than
the erase block size of the target MTD device, JFFS2 may not perform optimally. If the SIZE
specified is below 4096, the units are assumed to be KiB.
-c, --cleanmarker=SIZE
Write ´CLEANMARKER´ nodes with the size specified. It is not normally appropriate to specify a
size other than the default 12 bytes.
-n, --no-cleanmarkers
Do not write ´CLEANMARKER´ nodes to the beginning of each erase block. This option can be useful
for creating JFFS2 images for use on NAND flash, and for creating images which are to be used on a
variety of hardware with differing eraseblock sizes.
-o, --output=FILE
Write JFFS2 image to file FILE. Default is the standard output.
-l, --little-endian
Create a little-endian JFFS2 image. Default is to make an image with the same endianness as the
host.
-b, --big-endian
Create a big-endian JFFS2 image. Default is to make an image with the same endianness as the
host.
-D, --devtable=FILE
Use the named FILE as a device table file, for including devices and changing permissions in the
created image when the user does not have appropriate permissions to create them on the file
system used as source.
-f, --faketime
Change all file timestamps to ´0´ for regression testing.
-q, --squash
Squash permissions and owners, making all files be owned by root and removing write permission for
´group´ and ´other´.
-U, --squash-uids
Squash owners making all files be owned by root.
-P, --squash-perms
Squash permissions, removing write permission for ´group´ and ´other´.
--with-xattr
Enables xattr, stuff all xattr entries into jffs2 image file.
--with-selinux
Enables xattr, stuff only SELinux Labels into jffs2 image file.
--with-posix-acl
Enable xattr, stuff only POSIX ACL entries into jffs2 image file.
-m, --compression-mode=MODE
Set the default compression mode. The default mode is priority which tries the compressors in a
predefinied order and chooses the first successful one. The alternatives are: none (mkfs will not
compress) and size (mkfs will try all compressor and chooses the one which have the smallest
result).
-x, --disable-compressor=NAME
Disable a compressor. Use -L to see the list of the available compressors and their default
states.
-X, --enable-compressor=NAME
Enable a compressor. Use -L to see the list of the available compressors and their default states.
-y, --compressor-priority=PRIORITY:NAME
Set the priority of a compressor. Use -L to see the list of the available compressors and their
default priority. Priorities are used by priority compression mode.
-L, --list-compressors
Show the list of the available compressors and their states.
-t, --test-compression
Call decompress after every compress - and compare the result with the original data -, and some
other check.
-h, --help
Display help text.
-v, --verbose
Verbose operation.
-V, --version
Display version information.
-i, --incremental=FILE
Generate an appendage image for FILE. If FILE is written to flash and flash is appended with the
output, then it seems as if it was one thing.
LIMITATIONS
The format and grammar of the device table file does not allow it to create symbolic links when the
symbolic links are not already present in the root working directory.
However, symbolic links may be specified in the device table file using the l type for the purposes of
setting their permissions and ownership.
BUGS
JFFS2 limits device major and minor numbers to 8 bits each. Some consider this a bug.
mkfs.jffs2 does not properly handle hard links in the input directory structure. Currently, hard linked
files will be expanded to multiple identical files in the output image.
AUTHORS
David Woodhouse
Manual page written by David Schleef <ds@schleef.org>
SEE ALSO
mkfs(8), mkfs.jffs(1), fakeroot(1)
MKFS.JFFS2(1)