JFFS2 is the second generation of the Journalling Flash File System for use on diskless embedded devices. It provides improved wear levelling, compression and support for hard links. You cannot use this on normal block devices, only on 'MTD' devices. Further information on the design and implementation of JFFS2 is available at <http://sources.redhat.com/jffs2/>.
This controls the amount of debugging messages produced by the JFFS2 code. Set it to zero for use in production systems. For evaluation, testing and debugging, it's advisable to set it to one. This will enable a few assertions and will print debugging messages at the KERN_DEBUG loglevel, where they won't normally be visible. Level 2 is unlikely to be useful - it enables extra debugging in certain areas which at one point needed debugging, but when the bugs were located and fixed, the detailed messages were relegated to level 2. If reporting bugs, please try to have available a full dump of the messages at debug level 1 while the misbehaviour was occurring.
This enables the write-buffering support in JFFS2. This functionality is required to support JFFS2 on the following types of flash devices: - NAND flash - NOR flash with transparent ECC - DataFlash
This causes JFFS2 to read back every page written through the write-buffer, and check for errors.
This feature makes it possible to use summary information for faster filesystem mount. The summary information can be inserted into a filesystem image by the utility 'sumtool'. If unsure, say 'N'.
Extended attributes are name:value pairs associated with inodes by the kernel or by users (see the attr(5) manual page, or visit <http://acl.bestbits.at/> for details). If unsure, say N.
Posix Access Control Lists (ACLs) support permissions for users and groups beyond the owner/group/world scheme. To learn more about Access Control Lists, visit the Posix ACLs for Linux website <http://acl.bestbits.at/>. If you don't know what Access Control Lists are, say N
Security labels support alternative access control models implemented by security modules like SELinux. This option enables an extended attribute handler for file security labels in the jffs2 filesystem. If you are not using a security module that requires using extended attributes for file security labels, say N.
Enabling this option allows you to explicitly choose which compression modules, if any, are enabled in JFFS2. Removing compressors can mean you cannot read existing file systems, and enabling experimental compressors can mean that you write a file system which cannot be read by a standard kernel. If unsure, you should _definitely_ say 'N'.
Zlib is designed to be a free, general-purpose, legally unencumbered, lossless data-compression library for use on virtually any computer hardware and operating system. See <http://www.gzip.org/zlib/> for further information. Say 'Y' if unsure.
minilzo-based compression. Generally works better than Zlib. This feature was added in July, 2007. Say 'N' if you need compatibility with older bootloaders or kernels.
Rtime does manage to recompress already-compressed data. Say 'Y' if unsure.
RUBINMIPS and DYNRUBIN compressors. Say 'N' if unsure.
You can set here the default compression mode of JFFS2 from the available compression modes. Don't touch if unsure.
Uses no compression.
Tries the compressors in a predefined order and chooses the first successful one.
Tries all compressors and chooses the one which has the smallest result.
Tries all compressors and chooses the one which has the smallest result but gives some preference to LZO (which has faster decompression) at the expense of size.