[PATCH] Make the mtdblock read/write skip the bad nand sector
David Woodhouse
dwmw2 at infradead.org
Mon Nov 25 07:16:10 EST 2013
On Mon, 2013-11-25 at 08:52 -0300, Ezequiel Garcia wrote:
>
> Your understanding is correct: NAND *must* be erased explictly in
> userspace
> before writing. However, keep in mind the following additional
> constraints:
>
> * Writing should be always performed using 'nandwrite',
> not tools such as 'cat' or 'dd'.
>
> * An mtdblock shouldn't be used to access directly the NAND from
> userspace. AFAICS, the primarily usage of mtdblock is to be able to
> mount JFFS2.
No. You don't need mtdblock to mount JFFS2 at all.
The mtdblock driver was used in the *very* early days of the MTD system,
on NOR flash with a "traditional" file system. Either in read-only mode
for something like cramfs, or in a very unsafe writeable mode. We
actually put ext2 on it for the Compaq iPaq for a while, before we had
JFFS.
It was used as a shortcut for mounting JFFS2, and still is by a lot of
people, but it's certainly not necessary. You can turn off CONFIG_BLOCK
entirely and still use JFFS2.
You should consider mtdblock to be the most basic, primitive, "flash
translation layer" that can possibly exist. And thus, should basically
never use it. I certainly don't approve of trying to extend it.
--
dwmw2
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 5745 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-mtd/attachments/20131125/e16225f5/attachment-0001.bin>
More information about the linux-mtd
mailing list