Re: usb-storage: how to ruin your hardware(?)

[Brandon Stewart]

I think what Matt is saying is that certain functionality of the USB 
device is soft-coded. So once this data is gone from the device, trying 
to write to or from it will fail, since the read and write commands are 
(partially) soft-coded. If this is true, then writing to this device is 
like trying to ping a computer that was booted up, but had no operating 
system loaded. It would seem weird to create a device in such a manner, 
but it is not outside the realm of possibility.

I had a printer (hp lj1000) that operated in exactly this fashion. To 
work, its firmware needed to be cat'ed to the device before any printing 
was done. I never got this working and instead just returned the printer 
and replaced it with a postscript compliant model. I recommend that you 
do similar. No sense eating the cost. It will be impetus for the 
manufacturers to make robust and compatible devices.

-Brandon

H.Rosmanith (Kernel Mailing List) wrote:

> -- Start of PGP signed section.
>  
>
> > For the vast majority of USB storage devices, it's not possible to kill the
> > device like you did.
> >
> > It looks like the device firmware needs certain data on the first sector to
> > operate.  The usb-storage communication is working just fine, but the
> > device is refusing commands.
> >    
>
> aha. do you know why the device is refusing commands? it relys on sector0
> to contain some vital information and if this is not there, it refuses
> commands?
>
>
>  
>
> > Likely, the unit is unrecoverable unless you can figure out the magic that
> > the manufacturer uses to write that beginning few sectors of data.
> >    
>
> pfhew....I once sent an email to Prolific (manufacturer of this device), but
> never got an answer. so, one needs the layout of the first sectors and
> a method how to write that ... I wonder if Prolific has this info on their
> website ...
>
>
>  
>
> > Matt
> >
> > P.S.  I commonly put ext2/3 filesystems on my CF cards without any
> > problems.
> >
> > P.P.S. The 'strange partition table' you saw probably wasn't a partition
> > table at all -- it was likely the start of a VFAT filesystem.  I'm guessing
> > that if you had just mounted /dev/sda (notice no partition number!), it
> > would have worked.
> >    
>
> I see. the whole flash disk is a single filesystem without partitions
> (I used to format HDs this way in the old days :->
>
> do you think it is possible to "mke2fs /dev/sda" (once I return the
> USB BAR to the vendor and tell them it's "somehow damaged, no idea
> why") on a new  

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