Misunderstanding of embedded system designers [LWN.net]

Misunderstanding of embedded system designers

Posted Jan 20, 2006 6:36 UTC (Fri) by hingo (subscriber, #14792)
In reply to: Misunderstanding of embedded system designers by im14u2c
Parent article: GPLv3: a first look

You mean you have take a hash of the final executable and the hardware will only run that and nothing else? I'm not sure on this one, but that may in fact be allowable (there is no secret key to give away, so you have given the user everything there is). It may not be very wise however, because if there is a bug in your software you cannot update it anymore, you'd have to replace the entire device. (If there is a non-hardware way to update it, the license requires you to provide the user with that mecanism.)

Therefore the wiser thing to do is what Karim above wants to do, have the firmware check whether the executable is signed with a particular key. This way you can later produce updates and sign them. On this issue the v3 is very clear. You have to either a) provide the user with the secret key needed, or (more likely) b) enable the user to alter the device such that he can use another key of his own without losing any functionality because of that.

While I'm writing here, I'll reply to Karim as well: Obviously, the GPL cannot dictate the hardware license. You can build such hardware if you want, and if your software is GPLv3 you'll have to include the secret key. Sorry boy, you are just worng and confused, and you should let go already. (For the benefit of everybody, I don't intend to continue this thread although I fully expect Karim will do so.)

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Misunderstanding of embedded system designers

Posted Jan 20, 2006 20:50 UTC (Fri) by karim (subscriber, #114) [Link]

Feel free to paint my position in whichever color makes you feel better. But here's the quote from the license:

"Complete Corresponding Source Code also includes any encryption or authorization codes necessary to install and/or execute the source code of the work, perhaps modified by you, in the recommended or principal context of use, such that its functioning in all circumstances is identical to that of the work, except as altered by your modifications."

And what I suggest does exactly that. The kernel's behavior hasn't changed, its functioning is identical. It's the hardware beneath that isn't functioning the same way from the point of view of the user space applications accessing it ...

If confusion there is, I don't believe it's on my side.

Karim