Re: jffs2: Too few erase blocks (1)

Dzuy Nguyen
2009-02-09T15:38:44Z

Thanks, Ricard. I didn't realize that jffs2 is not suitable for a small
partition. Yes,
64K is all I can afford. I suppose I can dd the file, but doesn't that
provide no wear
leveling feature that jffs2 does?

Ricard Wanderlof wrote:
> On Mon, 9 Feb 2009, Dzuy Nguyen wrote:
>
>
>> I've allocated a small (64K) "user_config" partition in my flash for
>> persistence storage:
>>
>> mtd0: 00020000 00010000 "u-boot"
>> mtd1: 00010000 00010000 "Config"
>> mtd2: 00100000 00010000 "vmlinux"
>> mtd3: 002a0000 00010000 "rootfs"
>> mtd4: 00010000 00010000 "user_config"
>> mtd5: 00020000 00010000 "ART"
>>
>> When I tried to mount -t jffs2 /dev/mtdblock4, I get
>>
>> jffs2: Too few erase blocks (1)
>>
>> I understand that my erasesize is 64K, which gives me only 1 block,
>> and jffs2 needs more than 1 block, but the kernel defaults the erasesize
>> to 64K.
>>
>
> The kernel does that probably because that is the size of the blocks on
> your flash chip. It is not so much a default as detection of the
> properties of the chip.
>
>
>> If I made a jffs2 file with eraseblock=8, would this work or would I have
>> to set it at the kernel?
>>
>
> You need to allocate more space if you want to use jffs2 quite simply. The
> exact number is not exact; 8 should be ok, meaning you need to partition
> your flash so you have 64K * 8 = 512K in your user_config partition.
>
> If you can't afford that much space, you could consider writing your user
> configurations to a file and just dumping the file with dd into your flash
> partition. Not at all as flexible, but doable in a pinch.
>
> /Ricard
> --
> Ricard Wolf Wanderlöf ricardw(at)axis.com
> Axis Communications AB, Lund, Sweden www.axis.com
> Phone +46 46 272 2016 Fax +46 46 13 61 30
>
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