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Diffstat (limited to 'u-boot/doc/README.JFFS2')
| -rw-r--r-- | u-boot/doc/README.JFFS2 | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/u-boot/doc/README.JFFS2 b/u-boot/doc/README.JFFS2 new file mode 100644 index 0000000..f0e9bc1 --- /dev/null +++ b/u-boot/doc/README.JFFS2 @@ -0,0 +1,74 @@ +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). |