Re: [microblaze-uclinux] JFFS2 NAND Flash support in uClinux 2.4.x??

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi David,

David Summers wrote:

> Would I be better off just using a compact flash card?  My current
> development board does not have a SystemACE controller on it.  Are compact
> flash cards (other than SystemACE) well supported under uCLinux?

The basic CF layer (esentially just IDE) should work directly.  You'd
need some kind of OPB -> IDE interface - perhaps you could fake it with
the OPB_EMC and some glue logic?

The nice thing about SysAce is that this is all done for you, at the
cost of an extra part on the board.  But, it also gives you a
configuration solution in the mix.

> The only catch is that my application does not allow me to shut down the
> system gracefully.  Power could be pulled at any time and I worry about
> corrupting the file system on a FAT32 formatted CF card.  

Yep, that would be bad.

> Are there any
> Linux filesystems that I could use with a compact flash (or SD/MMC) card
> that would prevent filesystem corruption in the event of an abrupt power
> down?

The Linux (and uClinux) sysace drivers just present a block device - so
you should be able to mount just about anything on it.  I'd have to
check to be sure, but you should be able to mount JFFS2 directly onto
sysace.   You don't want a regular journalling file system (ext2, ext3),
the wear pattern will do bad things to your flash eventually.

What sort of data rates are you looking at?  That could be a big factor
in all of this.

John
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