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howto jffs2 + mtd

DISCUSSION Felix Joussein 2 participants 3 messages Sep 11, 2006 1 message not in the archive Memory technology devices (MTD)

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Felix Joussein

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Hello list,

I would like to create a jffs2 filesystem on to an ordinary fresh- out of the box 512 Kingston Datatraveller USB Stick. As I later want to boot from it, I performed the following steps:

fdisk /dev/sda
create 2 partitions
sda1, sda2

syslinux /dev/sda1
mount /dev/sda1 /mnt
cp $allYouNeedToBoot /dev/sda1
umount /mnt

Here now the mtd part:
modprobe block2mtd
echo "/dev/sda2" > /sys/module/block2mtd/parameters/block2mtd cat /proc/mtd
mtd0: 0f480000 00001000 "block2mtd: /dev/sda2"

now I read in the internet 2 different commands:
either flash_eraseall -j /dev/mtd0
or flash_erase /dev/mtd0 0 00001000

Regardless of what I do, I am not able to mount -t jffs2 /dev/mtdblock0 /mnt
Either I get dmesg "mount jffs2_scan_eraseblock(): magic bitmask 0x1985 not found" on all consoles, the only way to stop this is to reboot, or I wait approx. 10 Mins, then I get

CPU:    0
EIP:    0060:[<d09bd77f>]    Not tainted VLI
EFLAGS: 00010206   (2.6.17.13-fwgw #1)

EIP is at block2mtd_erase+0x9b/0x148 [block2mtd]
eax: d0000000 ebx: d0003000 ecx: c11fffe0 edx: c11fffe0
esi: c11fffe0 edi: c11fffe0 ebp: 00000001 esp: c1325eb8
ds: 007b es: 007b ss: 0068
Process pdflush (pid: 216, threadinfo=c1324000 task=cfffa540)

Stack: cecc278c 0000dee8 cfe8c368 cf42a340 c1325efc cf42a370 d129db80 c020209a
      cecc260c cf42a340 ced258d0 ced258d8 ced2592c ced258f8 00002000 
00000000
      0dee9000 20031985 0000000c e41eb0b1 c1325efc 0000000c 00001000 
0000000c
Call Trace:
<c020209a> jffs2_erase_pending_blocks+0x21a/0x736  <c0202a02> jffs2_write_super+0x26/0x34
<c015eb42> sync_supers+0x96/0xd4  <c0141ee0> pdflush+0x0/0x1a0
<c0141686> wb_kupdate+0x26/0xd8  <c0141fc6> pdflush+0xe6/0x1a0
<c0141660> wb_kupdate+0x0/0xd8  <c0130d97> kthread+0xbf/0xd8
<c0130cd8> kthread+0x0/0xd8  <c0100cd5> kernel_thread_helper+0x5/0xc
Code: ff ff 0f 87 c0 00 00 00 50 e8 72 83 78 ef 8d 98 00 40 00 00 56 e8 66 83 78 ef 5a 59 39 c3 77 0b eb 3c 89 f6 83 c0 04 39 c3 76 33 <83> 38 ff 74 f4 90 0f ba 2e 00 19 c0 85 c0 75 36 56 e8 3f 83 78
EIP: [<d09bd77f>] block2mtd_erase+0x9b/0x148 [block2mtd] SS:ESP 0068:c1325eb8
BUG: warning at kernel/exit.c:855/do_exit()
<c012296c> do_exit+0x83c/0x850  <c01147ff> bust_spinlocks+0x3f/0x48
<c0104580> do_trap+0x0/0xd4  <c0114c6f> do_page_fault+0x353/0x5f4
<c011491c> do_page_fault+0x0/0x5f4  <c0103c43> error_code+0x4f/0x54
<d09bd77f> block2mtd_erase+0x9b/0x148 [block2mtd]  <c020209a> jffs2_erase_pending_blocks+0x21a/0x736
<c0202a02> jffs2_write_super+0x26/0x34  <c015eb42> sync_supers+0x96/0xd4
<c0141ee0> pdflush+0x0/0x1a0  <c0141686> wb_kupdate+0x26/0xd8
<c0141fc6> pdflush+0xe6/0x1a0  <c0141660> wb_kupdate+0x0/0xd8
<c0130d97> kthread+0xbf/0xd8  <c0130cd8> kthread+0x0/0xd8
<c0100cd5> kernel_thread_helper+0x5/0xc

But: the filesystem is mounted.
How ever, accessing /mnt is not possible then... again: reboot is the only way out...

I would be very thankfull, if anybody could help me with this.

Thanks,

Felix Joussein

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#1 lore raw
Quoted 21 lines · Felix Joussein

Hello list,

I would like to create a jffs2 filesystem on to an ordinary fresh- out of the box 512 Kingston Datatraveller USB Stick.
As I later want to boot from it, I performed the following steps:

fdisk /dev/sda
create 2 partitions
sda1, sda2

syslinux /dev/sda1
mount /dev/sda1 /mnt
cp $allYouNeedToBoot /dev/sda1
umount /mnt

Here now the mtd part:
modprobe block2mtd
echo "/dev/sda2" > /sys/module/block2mtd/parameters/block2mtd cat /proc/mtd
mtd0: 0f480000 00001000 "block2mtd: /dev/sda2"

Quoted 3 lines

now I read in the internet 2 different commands:
either flash_eraseall -j /dev/mtd0
or flash_erase /dev/mtd0 0 00001000

You do not need that on the mtdblock device. This is only useful on real flash devices, i.e. physicall mapped flash devices, not USB sticks or CF cards.

[...]

Quoted 4 lines

I would be very thankfull, if anybody could help me with this.

Thanks,
Felix Joussein

Cheers
nils

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#3 lore raw
In reply to a message not in the archive
Quoted 4 lines · Felix Joussein
Quoted 3 lines

You do not need that on the mtdblock device. This is only useful on real flash devices, i.e. physicall mapped flash devices, not USB sticks or CF cards.

So, how else do I get a jffs2 filesystem on my usb or cf?

Oh, sorry, I should have been more precise.
You do not need the flash_erase or flash_erase_all. The rest of the process is the same.

Quoted 2 lines

As I understand any other filesystem would shredder my usb-stick after a approx. 1 mio writes?

But anyway, JFFS2 is not a very good idea on a USB stick. The problem is that the stick's flash controller already does wear levelling and error correction for you, transparantly.
With JFFS2 you might end up with doing the process twice which might result in even worse performance than with a "normal" filesystem, like EXT2. You should be pretty safe with an ext2 if you mount it with "noatime" option and if possible, read-only.

Quoted 2 lines

Thanks again,
Felix

Cheers
nils

Signature · 4 lines
kernel concepts GbR      Tel: +49-271-771091-12
Dreisbachstr. 24         Fax: +49-271-771091-19
D-57250 Netphen          Mob: +49-176-21024535
--