mtd_debug usage

[Duke]

I've added a few comments and results below:

On 11/21/06, Duke <ezbonites at gmail.com> wrote:
> Hi All,
> I'm having a bit of trouble understanding the usage to mtd_debug.
>
> With the usage format below, why would I need <offset> and <len> if
> the mtdblock sizes are already known? (i.e at boot)
> I always thought if I write "mtd_debug erase /dev/mtdblock2" it will
> erase the entire /dev/mtdblock2 device. not so?
> If not, do I specify "mtd_debug erase /dev/mtdblock2 0x0 0x600000" for
> mtdblock2 where 0x0 indicated the start of the block?
>
> When I do a write "mtd_debug write /dev/mtdblock2 0x0 0x600000 myfs.cramfs"
> would it do just this?
>
> I've seen usage where /dev/mtd2 is used instead of /dev/mtdblock2,
> what is the difference here? which should it be. It seems to me that
> /dev/mtd2 simply gives the node info (mtd_debug info )and
> /dev/mtdblock2 is really what you want to used. Do I have this
> correct?
>
> usage: mtd_debug info <device>
>        mtd_debug read <device> <offset> <len> <dest-filename>
>        mtd_debug write <device> <offset> <len> <source-filename>
>        mtd_debug erase <device> <offset> <len>
>

cfi_cmdset_0001: Erase suspend on write enabled
3 cmdlinepart partitions found on MTD device physmap-flash.0
Creating 3 MTD partitions on "physmap-flash.0":
0x00000000-0x00040000 : "boot"
0x00040000-0x00200000 : "kernel"
0x00200000-0x00800000 : "cramfs"

When I ran mtd_debug I get the following from the above mapping:

# mtd_debug info /dev/mtd2
mtd.type = MTD_NORFLASH
mtd.flags =
mtd.size = 1835008 (1M)
mtd.erasesize = 262144 (256K)
mtd.oobblock = 1
mtd.oobsize = 0
mtd.ecctype = MTD_ECC_NONE
regions = 0

# mtd_debug info /dev/mtd1
mtd.type = MTD_NORFLASH
mtd.flags =
mtd.size = 262144 (256K)
mtd.erasesize = 262144 (256K)
mtd.oobblock = 1
mtd.oobsize = 0
mtd.ecctype = MTD_ECC_NONE
regions = 0

# mtd_debug info /dev/mtd0
mtd.type = MTD_NORFLASH
mtd.flags =
mtd.size = 262144 (256K)
mtd.erasesize = 262144 (256K)
mtd.oobblock = 1
mtd.oobsize = 0
mtd.ecctype = MTD_ECC_NONE
regions = 0

# mtd_debug info /dev/mtd3
mtd.type = MTD_NORFLASH
mtd.flags =
mtd.size = 1835008 (1M)
mtd.erasesize = 262144 (256K)
mtd.oobblock = 1
mtd.oobsize = 0
mtd.ecctype = MTD_ECC_NONE
regions = 0

# mtd_debug erase /dev/mtdblock2 0 0x600000
MEMERASE: Inappropriate ioctl for device
# mtd_debug erase /dev/mtd2 0 0x600000
Erased 6291456 bytes from address 0x00000000 in flash
# mtd_debug write /dev/mtd2 0 0x600000 myfs_cramfs
file_to_flash: fread, size 0x600000, n 0x600000
fread(): Success

However, I expected mtd3 to show no info, but it did.
Even though it said a successful write, it did not as I could not
mount from that partition.

Clearly I'm missing something here. Could someone help me understand this?

much thanks