xref: /openbmc/u-boot/doc/README.JFFS2 (revision 274bced8)
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 boot from a partition which is mounted writable, and you
14update your boot environment by replacing single files on that
15partition, you should also define CONFIG_SYS_JFFS2_SORT_FRAGMENTS. Scanning
16the JFFS2 filesystem takes *much* longer with this feature, though.
17Sorting is done while inserting into the fragment list, which is
18more or less a bubble sort. That algorithm is known to be O(n^2),
19thus you should really consider if you can avoid it!
20
21
22There only one way for JFFS2 to find the disk. It uses the flash_info
23structure to find the start of a JFFS2 disk (called partition in the code)
24and you can change where the partition is with two defines.
25
26CONFIG_SYS_JFFS2_FIRST_BANK
27	defined the first flash bank to use
28
29CONFIG_SYS_JFFS2_FIRST_SECTOR
30	defines the first sector to use
31---
32
33TODO.
34
35	Remove the assumption that JFFS can dereference a pointer
36	into the disk. The current code do not work with memory holes
37	or hardware with a sliding window (PCMCIA).
38