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From: Dzuy Nguyen <dzuy@infinity-studios.com>
To: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>
Subject: Re: jffs2: Too few erase blocks (1)
Date: Mon, 09 Feb 2009 09:39:52 -0600	[thread overview]
Message-ID: <49904E48.7000805@infinity-studios.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0902090947080.19761@lnxricardw.se.axis.com>

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
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>   

  reply	other threads:[~2009-02-09 15:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-02-09  5:52 jffs2: Too few erase blocks (1) Dzuy Nguyen
2009-02-09  8:50 ` Ricard Wanderlof
2009-02-09 15:39   ` Dzuy Nguyen [this message]
2009-02-09 16:32     ` Ricard Wanderlof
2009-02-10  4:16       ` Dzuy Nguyen
2009-02-10 12:41         ` Jamie Lokier

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