Re: [Yaffs] How to use YAFFS2 on large NAND partition(4GB)?

On Friday 30 March 2007 15:58, you wrote:
> I will check it out, thank you, Charles.
> Another question, my arm kernel (patched from linux-2.6.20-rc1) has a 4GB
> limitation for MTD partition(the data type of mtd->size is 32bit integer,
> it overflowed for 4GB size!), so how to create partition as large as 6GB,
> even 8GB?

I can only speak for the actual yaffs part. You will need to ensure thet the
mtd works too.

The testing to 8GB that I did was in a yaffs direct test harness.

YAFFS does not use byte addressing internally. YAFFS works with units of
"chunks" which typically equate to 512 or 2048 bytes, and YAFFS can support
up to 2^31 of those whish is a lot of storage. In reality, RAM and other
resources wiull be exhausted first.

The 6GB size was done by someone using modified mtd drivers (because they
wanted faster speed than the mtd).

The mtd **should** be using loff_t for all addresses and sizes. If it is not,
well then mtd is broken because it supports loff_t for byte addresses. I just
pulled the tarball from www.kernel.org and it does look like mtd is broken in
this respect. I suggest you fix the problem and submit patches to the mtd
group.

When you are working with very large NAND arrays (bigger than 2G or so), it
also makes sense to use larger "virtual page" sizes. eg. Instead of using
blocks of 64x2048 bytes, make this look like 32x4096 bytes. That reduces some
of the management overheads.

-- Charles


>
> >From: Charles Manning <manningc2@actrix.gen.nz>
> >To: yaffs@lists.aleph1.co.uk
> >Subject: Re: [Yaffs] How to use YAFFS2 on large NAND partition(4GB)?
> >Date: Fri, 30 Mar 2007 07:45:26 +1200
> >
> >On Friday 30 March 2007 06:57, Tian Jin wrote:
> > > Hi, I know YAFFS2 has a NAND partition size limitation of 2GB, but I
> >
> >have
> >
> > > to use a 3~4GB large NAND partition(3 or 4 x 1GB NAND chips) to storage
> > > audio data.
> >
> >That limit was removed a while ago. People are using YAFFS on partitions
> > at least as large as 6GBytes and I have tested up to 8GB on simulations.
> >
> >-- CHarles
> >
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