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


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
>>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 ...
>>P.S. I commonly put ext2/3 filesystems on my CF cards without any
>>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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