Large flash concatenation

David Woodhouse dwmw2 at
Fri May 28 06:28:43 EDT 2004

On Fri, 2004-05-28 at 10:41 +0100, Andy Hawkins wrote:
> Hi,
> I'm trying to add support to the kernel for concatenating a number of
> large flash devices (1Gb Samsung K9F1G08).
> I've added the following line to nand_ids.c:
> 	{"NAND 1GiB 3,3V", 0xf1, 30, 0x4000, 0},

Er, that part is 1Gib, not 1GiB. 1Gib is 128MiB.

> I want to be able to use these multiple chips as a single flash
> filesystem (probably JFFS2).

That's a lot of flash -- JFFS2 doesn't scale too well at the moment.

To make JFFS2 work better, we need to reduce the memory usage -- partly
by reducing the size of some structures (we can drop totlen from the
jffs2_raw_node_ref with a bit of effort), and partly by reducing the
_number_ of such structures -- perhaps we should increase the maximum
data payload on a single node from 4KiB to 16KiB or more -- thereby
reducing the number of nodes a lot.

We also really need to do checkpointing to reduce mount time.

It would be interesting to try JFFS2 -- but I suspect you may do better
with YAFFS2 at the moment.


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