README.JFFS2
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JFFS2 options and usage.
-----------------------
JFFS2 in U-Boot is a read only implementation of the file system in
Linux with the same name. To use JFFS2 define CONFIG_CMD_JFFS2.
The module adds three new commands.
fsload - load binary file from a file system image
fsinfo - print information about file systems
ls - list files in a directory
chpart - change active partition
If you boot from a partition which is mounted writable, and you
update your boot environment by replacing single files on that
partition, you should also define CONFIG_SYS_JFFS2_SORT_FRAGMENTS. Scanning
the JFFS2 filesystem takes *much* longer with this feature, though.
Sorting is done while inserting into the fragment list, which is
more or less a bubble sort. That algorithm is known to be O(n^2),
thus you should really consider if you can avoid it!
There is two ways for JFFS2 to find the disk. The default way uses
the flash_info structure to find the start of a JFFS2 disk (called
partition in the code) and you can change where the partition is with
two defines.
CONFIG_SYS_JFFS2_FIRST_BANK
defined the first flash bank to use
CONFIG_SYS_JFFS2_FIRST_SECTOR
defines the first sector to use
The second way is to define CONFIG_SYS_JFFS_CUSTOM_PART and implement the
jffs2_part_info(int part_num) function in your board specific files.
In this mode CONFIG_SYS_JFFS2_FIRST_BANK and CONFIG_SYS_JFFS2_FIRST_SECTOR is not
used.
The input is a partition number starting with 0.
Return a pointer to struct part_info or NULL for error;
Ex jffs2_part_info() for one partition.
---
#if defined CONFIG_SYS_JFFS_CUSTOM_PART
#include <jffs2/jffs2.h>
static struct part_info part;
struct part_info*
jffs2_part_info(int part_num)
{
if(part_num==0){
if(part.usr_priv==(void*)1)
return ∂
memset(&part, 0, sizeof(part));
part.offset=(char*)0xFF800000;
part.size=1024*1024*8;
/* Mark the struct as ready */
part.usr_priv=(void*)1;
return ∂
}
return 0;
}
#endif
---
TODO.
Remove the assumption that JFFS can dereference a pointer
into the disk. The current code do not work with memory holes
or hardware with a sliding window (PCMCIA).