howto jffs2 + mtd

howto jffs2 + mtd

[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"

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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Re: howto jffs2 + mtd

[Nils Faerber]

Felix Joussein schrieb:
> 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

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.

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

> Thanks,
> Felix Joussein
Cheers
  nils

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Re: howto jffs2 + mtd

[Nils Faerber]

Felix Joussein schrieb:
>> 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.

> 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.

> Thanks again,
> Felix
Cheers
  nils

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