xref: /openbmc/u-boot/doc/README.JFFS2 (revision de9ac9a1)
1JFFS2 options and usage.
2-----------------------
3
4JFFS2 in U-Boot is a read only implementation of the file system in
5Linux with the same name. To use JFFS2 define CONFIG_CMD_JFFS2.
6
7The module adds three new commands.
8fsload  - load binary file from a file system image
9fsinfo  - print information about file systems
10ls      - list files in a directory
11chpart  - change active partition
12
13If you do now need the commands, you can enable the filesystem separately
14with CONFIG_FS_JFFS2 and call the jffs2 functions yourself.
15
16If you boot from a partition which is mounted writable, and you
17update your boot environment by replacing single files on that
18partition, you should also define CONFIG_SYS_JFFS2_SORT_FRAGMENTS. Scanning
19the JFFS2 filesystem takes *much* longer with this feature, though.
20Sorting is done while inserting into the fragment list, which is
21more or less a bubble sort. That algorithm is known to be O(n^2),
22thus you should really consider if you can avoid it!
23
24
25There only one way for JFFS2 to find the disk. It uses the flash_info
26structure to find the start of a JFFS2 disk (called partition in the code)
27and you can change where the partition is with two defines.
28
29CONFIG_SYS_JFFS2_FIRST_BANK
30	defined the first flash bank to use
31
32CONFIG_SYS_JFFS2_FIRST_SECTOR
33	defines the first sector to use
34---
35
36TODO.
37
38	Remove the assumption that JFFS can dereference a pointer
39	into the disk. The current code do not work with memory holes
40	or hardware with a sliding window (PCMCIA).
41