OS Builder output img ?

[Richard Smith]

On Mon, Mar 25, 2013 at 7:07 PM, James Cameron <quozl at laptop.org> wrote:
> On Mon, Mar 25, 2013 at 06:50:00PM -0400, Richard Smith wrote:

>> > But maybe you don't need to do that, if you are only changing one tag?
>> > How many tags are you changing?  If one, then finish the script with
>> > the tag change.
>>
>> I mentioned that he could also disable security.  So he would be
>> deleting the 'wp' tag too.
>
> Really?  disable-security changes the wp tag to ww rather than
> deleting it.  Do you think he should delete it instead?

The effect is the same.  We did ww and wp because 'w' is a 0x77 and
'p' is a 0x70 so you could change the w to a p with a single write
without an erase cycle in-between.  We never really used that feature
though.

> Is there a risk of having to reboot to enable writes?

I was just pondering this as well.  Its been a while,  but IIRC think
this may thwart any attempt to do it in a single pass.  The write
protect on the SPI flash is set very early so OFW has to issue a
special command to reboot without the lock.  No way around it as you
can only unlock with a reboot.  I suppose you could do the security
disable first and then when you see that its 'ww' rather than 'wp'
continue on with the re-flash and then the LO change as the last step.

-- 
Richard A. Smith
One Laptop per Child