David, On Mon, Nov 25, 2013 at 12:16:10PM +0000, David Woodhouse wrote: > 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. >
Thanks a lot for the insight. After reading this, I'm wondering what's preventing us from killing MTD block support altogether. Artem, already suggested it a while back... -- Ezequiel García, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
