OT: USB stick with write protect switch?

[Amedee Van Gasse (ub)]

On Sat, October 10, 2009 19:40, drew einhorn wrote:
> On Sat, Oct 10, 2009 at 10:59 AM, Amedee Van Gasse (on Ubuntu mailing
> lists) <amedee-ubuntu at amedee.be> wrote:
>> On Sat, October 10, 2009 18:29, Frans Ketelaars wrote:
>>> On Sat, 10 Oct 2009 09:13:44 -0600, drew einhorn wrote:
>>>
>>>> The convenience of booting from a USB stick is great!
>>>>
>>>> It would be even better to be able to flip a switch on the stick and
>>>> making it a read only device!
>>>>
>>>> Anybody know of a source?
>>>
>>> This one
>>> http://www.newegg.com/Product/Product.aspx?Item=N82E16820141488
>>> has a write protection switch .
>>
>> Can anyone confirm that these "hardware" R/O switches always work in all
>> circumstances and that there is no way whatsoever that software can
>> ignore
>> the write protect?
>>
>> Because I have read once that it was possible but I forgot to bookmark
>> the
>> source.
>>
>
> Hmm.  I had not thought of that issue.  From a hardware perspective I'm
> sure
> it is possible to design it either way.  It could just set a read only
> bit somewhere
> and depend on a driver to respect it.  Or, it could disconnect a
> signal necessary
> for writing.

That must have been it. Some read-only sticks only set a bit and rely on
the driver. If the driver doesn't respect the bit, then your write
protection is useless.
Other sticks really disable the write signal.

The problem is, it's hard to tell if you have "software"-based write
protection, or hardware-based. "software" in quotes.

You would actually have to find that circumventing method, and see if it
fails on your stick. If it fails, then you can be 99.9% sure that it is
really hardware-based.

-- 
Amedee