[E3-hacking] PBL V5.1

[Neil Stainton]

Sorry if this has been covered before, but can't the NOR flash be read
or rewritten simply by bit banging the memory bus via JTAG? The JTAG
port on the POMAP5910JGDY is IEEE 1149 compliant which I take to mean
that all the I/O on the device can be manually overidden.

Is the JTAG port brought out to a handy set of pads somewhere? If not,
are the appropriate balls brought out to vias underneath the CPU?

Neil


On Wed, 10 Oct 2007 11:12:27 +0100, "David Given" <dg at cowlark.com> said:
> Antony Stone wrote:
> [...]
> > It occurs to me that Amstrad don't want to release the keys they've used to 
> > sign/encrypt their new code, however the new 5.1 bootloader won't accept 
> > unsigned/unenecrypted code, and therefore we get a sort of stalemate.
> 
> AIUI, the reason why Amstrad are doing this in the first place is to 
> prevent people from buying up large numbers of emailers (which are sold 
> at a loss, remember), reflashing them, and then selling them on. This is 
> apparently fairly likely in eastern Europe.
> 
> [...]
> > That way Amstrad keeps its keys, but the devices which were released running 
> > Linux remain open for us to use as the GPL requires.
> 
> Except the whole point of the exercise is to *close* the device...
> 
> (And the GPL, v2 at least, *doesn't* require the devices be open. The 
> exact phrasing is:
> 
> &#8220;The source code for a work means the preferred form of the work for 
> making modifications to it. For an executable work, complete source code 
> means all the source code for all modules it contains, plus any 
> associated interface definition files, plus the scripts used to control 
> compilation and installation of the executable.&#8221;
> 
> PBL and the encryption keys are not covered by this. PBL because it's 
> not GPLd, and the encryption keys because they're not an interface 
> definition file or script.)
> 
> What they might be more likely to go with is a mechanism for obtaining 
> the key to an individual emailer --- either by paying them the 
> difference in price between what it cost to build and what it's sold at 
> (so that they don't end up out of pocket), or by just asking nicely; 
> they don't seem to have a problem with small numbers of hobbyists. 
> However, it's probably not possible to unlock an individual device. I 
> wouldn't have thought they'd have per-machine keys.
> 
> -- 
> David Given
> dg at cowlark.com
> 
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