running out of space dd'ing JFFS2 image to /dev/mtdblock/0

[Artem B. Bityuckiy]

On Mon, 31 Jan 2005, Robert P. J. Day wrote:

> On Mon, 31 Jan 2005, Josh Boyer wrote:
> 
> > On Mon, 2005-01-31 at 10:14 -0500, Robert P. J. Day wrote:
> > >   just for curiosity's sake, after i build a JFFS2 image using
> > > mkfs.jffs2, i want to mount out to verify its contents.  to do
> > > that, i use a recipe i patched together a while back involving
> > > loading the appropriate modules, creating /dev/mtdblock/0, dd'ing
> > > the image to that device, then mounting it.
> > >
> > >   however, this morning, in trying this with a larger-than-normal
> > > JFFS2 image, i get:
> > >
> > >   # dd bs=4096 if=soefsimage of=/dev/mtdblock/0
> > >   # dd: writing `/dev/mtdblock/0': No space left on device
> > >   1025+0 records in
> > >   1024+0 records out
> > >
> > > IOW, it dies after 4M.  is this a limit imposed by the ramdisk
> > > limit in the kernel configuration?  is this a configurable
> > > parameter at module load time?  thanks for any pointers.
> >
> > If you are using mtdram.c, it should be a module parameter.  Try
> > setting total_size to something larger.
> 
>   ah, excellent, but while we're on the subject of parameters, is
> there any hope of getting some consistency in the way parameter values
> are supplied across the world of JFFS2 and MTD?
> 
>   to wit, with "mkfs.jffs2":
> 
> -p, --pad[=SIZE] Pad output to SIZE bytes with 0xFF. If SIZE is
>                         not specified, the output is padded to the
> 			end of the final erase block
> 
> 
>   so, apparently, you supply an *exact* byte size here (it's not
> mentioned if you can use KiB or MiB prefixes).
> 
>   with "--pagesize" and "--eraseblock", the help states that you *can*
> use those prefixes.
> 
>   if you check what you can do with the mtdram module, you get:
> 
> $ modinfo mtdram
> filename:
> /lib/modules/2.6.10-1.741_FC3/kernel/drivers/mtd/devices/mtdram.ko
> parm:           total_size:Total device size in KiB
> parm:           erase_size:Device erase block size in KiB
> 
>   so the values here are ... what?  strictly in KiB?  so i'd supply
> something like
> 
>   total_size=16384
> 
> to specify 16M?  it's just a bit painful to jump around between the
> various utilities and have to keep remembering what the standard is.
> 
>   thoughts?
My thought that if you sent patch that fixes this inconsistency it will 
be nice. :-)

> 
> rday
> 
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> 

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.