mtd block readonly low level nand driver cramfs

[Max Stirling]

Max Stirling wrote:
> Max Stirling wrote:
>> I was looking at the chips folder under MTD and the MTD_ROM flag 
>> settings.
>>
>> I got this idea of having this low level driver code under chips with
>> the MTD_ROM flag set and mounting this for cramfs.
>>
>> Please comment, especially folks using the RO FS mounted on flash.
>>
>> MS
>>
>> On Jan 24, 2008 3:12 PM, Max Stirling <vicky.irobot at gmail.com> wrote:
>>  
>>> Hi,
>>>
>>> This might sound quite basic question. This is the first time I am
>>> looking into the MTD code so have some really basic questions.
>>>
>>> I am trying to mount a read only fs (cramfs) on the flash. Please 
>>> let me
>>> know if the following steps are right:
>>>
>>> 1. Enabled the following in the Kconfig files
>>>     CONFIG_MTD_PARITIONS
>>>     CONFIG_MTD
>>>     CONFIG_MTD_BLOCK_RO
>>>     CONFIG_MTD_NAND
>>>     CONFIG_MTD_NAND_IDS
>>>
>>>
>>> After booting the compiled kernel I am able to see the mtdblock under
>>> /proc/devices using 31 Major number.
>>>
>>> Now for me to mount the cramfs image that is on the flash I need to
>>> provide the low level nand driver code. This I need to write but before
>>> starting that can any one point me to a reference nand driver code that
>>> is used for read only mount? Which functionality would the MTD require
>>> to be implemented for mounting a cramfs image which is on the flash.
>>>
>>> Would appreciate any pointers to how to get started off with this.
>>>
>>> thanks in advance for the reply.
>>>
>>> M.S
>>>
>>>
>>>     
> When using the cramfs as the fs for the flash and mtdblock_ro enabled. 
> Which one should I be calling the user module, the cramfs or the 
> mtdblock_ro?
>
>
I have enabled the mtdblock_ro module and written a low lever chip 
driver code. Since I am mounting this as read-only I have set the type 
in mtd_info to MTD_ROM.


When I do a mount using command

# mount -t cramfs /dev/mtdblock mnt_cramfs
.
mtdblock_ro.c mtdblock_readsect
mtdblock_ro.c mtdblock_readsect
mtdblock_ro.c mtdblock_readsect
mtdblock_ro.c mtdblock_readsect
.
mount: Mounting /dev/mtdblock on cramfs failed: Invalid argument.

I created a cramfs image using cramfs utility and written that to flash. 
I tested the cramfs image by mounting on my local machine.

Is there anything that is missing here?

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