[newbie] MTD and tiny RAM

[newbie] MTD and tiny RAM

[free]

Hello,

I use a very tiny SRAM (128ko) battery backuped to save
very important and changeable data.
I have a char. driver for it (i know how to read/write it)
I would like to mount it on Linux VFS but it seems that
bloc drivers are RAM cached.
Acces on this SRAM must be immediatly apply (if power goes
down data must be safe)

Does MTD could help me :
- is my SRAM not to tiny (128KO) for use with MTD ?
- could i acces to my SRAM through MTD in block mode without caching ?
- what king of file system could fit on such tiny RAM ?


All advices are welcome.

Thanks

Damien

Re: [newbie] MTD and tiny RAM

[Jörn Engel]

On Thu, 26 September 2002 09:25:41 +0200, free wrote:
> I use a very tiny SRAM (128ko) battery backuped to save
> very important and changeable data.
> I have a char. driver for it (i know how to read/write it)
> I would like to mount it on Linux VFS but it seems that
> bloc drivers are RAM cached.
> Acces on this SRAM must be immediatly apply (if power goes
> down data must be safe)
> 
> Does MTD could help me :
> - is my SRAM not to tiny (128KO) for use with MTD ?
> - could i acces to my SRAM through MTD in block mode without caching ?
> - what king of file system could fit on such tiny RAM ?

(This assumes 128KO == 128 kilobyte)

You could use the slram driver for this and put a jffs2 on top of it.
But slram uses eraseblocks of 64kiB and jffs2 needs 5 of those free
for being operational. You should tweak the slram driver to use
something closer to 4kiB.

Jörn

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RE: [newbie] MTD and tiny RAM

[free]

>> I use a very tiny SRAM (128ko) battery backuped to save
>> very important and changeable data.
>> I have a char. driver for it (i know how to read/write it)
>> I would like to mount it on Linux VFS but it seems that
>> bloc drivers are RAM cached.
>> Acces on this SRAM must be immediatly apply (if power goes
>> down data must be safe)
>>
>> Does MTD could help me :
>> - is my SRAM not to tiny (128KO) for use with MTD ?
>> - could i acces to my SRAM through MTD in block mode without caching ?
>> - what king of file system could fit on such tiny RAM ?
>
>(This assumes 128KO == 128 kilobyte)
>
>You could use the slram driver for this and put a jffs2 on top of it.
>But slram uses eraseblocks of 64kiB and jffs2 needs 5 of those free
>for being operational. You should tweak the slram driver to use
>something closer to 4kiB.
>
>Jörn

I have a worry with jffs2, i use a kernel 2.2.17 and i was using an old CVS
snap shot. I have recently down load the last CVS and it does not compile
on my 2.2.17 kernel. My old CVS didn't have jffs2, it just have jffs.

Re: [newbie] MTD and tiny RAM

[David Woodhouse]

dag4004@free.fr said:
>  I have a worry with jffs2, i use a kernel 2.2.17 and i was using an
> old CVS snap shot. I have recently down load the last CVS and it does
> not compile on my 2.2.17 kernel. My old CVS didn't have jffs2, it just
> have jffs. 

It's been backported to 2.2. Look in the list archives.

--
dwmw2