[U-Boot] Interrupt autoboot by GPIO

[Florian Meier <florian.meier@koalo.de>]

Hi,
is there a possibility to interrupt autoboot when a GPIO pin has a
certain value? I know there is CONFIG_AUTOBOOT_DELAY_STR and that should
suffice in most cases when there is another peripheral connected to the
UART, but think about the following setup I have:

A processor (in my case a AR9331) has a single UART that is used as
U-Boot console. The same UART is connected to a radio transceiver.
Therefore, an attacker MIGHT send the CONFIG_AUTOBOOT_DELAY_STR to the
radio transceiver at the right time to insert malicious code.

I know, there are other possibilities to handle this (e.g. by ensuring
that the radio transceiver is only activated when the processor is
booted), but I think having a dedicated "interrupt autoboot"-button
would be an elegant solution.

What do you think?

Greetings,
Florian