MKFS.JFFS2(1)MKFS.JFFS2(1)NAMEmkfs.jffs2 - Create a JFFS2 file system image from directory
SYNOPSISmkfs.jffs2 [ -p,--pad[=SIZE] ] [ -r,-d,--root directory ] [ -s,--page‐
size=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 ] [ -m,--com‐
pression-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 con‐
tained 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 avaiable 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 ker‐
nel 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 cur‐
rent directory.
-s, --pagesize=SIZE
Use page size SIZE. The default is 4 KiB. This size is the
maximum size of a data node.
-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 tar‐
get 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 sys‐
tem 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´.
-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 avaiable
compressors and their default states.
-X, --enable-compressor=NAME
Enable a compressor. Use -L to see the list of the avaiable com‐
pressors and their default states.
-y, --compressor-priority=PRIORITY:NAME
Set the priority of a compressor. Use -L to see the list of the
avaiable compressors and their default priority. Priorities are
used by priority compression mode.
-L, --list-compressors
Show the list of the avaiable 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.
BUGS
JFFS2 limits device major and minor numbers to 8 bits each. Some con‐
sider 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 ALSOmkfs(8), mkfs.jffs(1), fakeroot(1)MKFS.JFFS2(1)
