how to disable/lock entering to bifboot by pressing ESC

[Petr Simandl]

The Biffboot serial console allows a 'silent' boot, but still responds
to the <ESC> key, which will drop you into the console menu.

Would it be please possible to disable or lock it to get no response
to the <ESC> key?

The reason, in our application, is that we have massive data flow at
serial port and sometimes it match <ESC> key and all gets stuck in in
waiting forever...

thanks
Petr

[nicolas le falher]

But if you disable this possibility, you can't access to bifboot for a new configuration :/.

Use a gpio with a transistor for stop TX to bifboot, and after boot, activate TX with gpio.
Or use an usb<->ttl module.

Nicolas

[biff...@yahoo.co.uk]

Hi Petr,

This requires a custom version of the bootloader for your
application. It's an easy change but you'll need JTAG, and I take no
responsibility for you bricking your device!

I won't ever produce a 'standard' version of Biffboot that will do
this. It's just too risky since the serial port is often the only way
into the device when there is a problem booting Linux. Of course, we
can have the button enabling the serial console instead (hold it down
when you power on), however there will be another group of users who
complain about that, and want to disable that too, so I can't really
win!

Perhaps the answer is using some 'fuse' bits in the boot flash sector,
where once you 'blow' them, you permanently change the behaviour, and
can't change it back again. I guess we could have a kind of 'activate
bootloader on button press' fuse, once it's programmed, the serial
console no longer responds to <ESC> but activates when the button is
held down. We'd have to make it hard for the user to blow the fuse by
mistake. There are a few options: Blow it via JTAG (completely
safe), blow from the bootloader, with lots of 'are you really sure'
type questions, or (more dangerous) use some utility to blow them from
within OpenWrt, although that requires a change to the patches, as I
think the bootloader is read-only at the moment.

Another option I've just thought of is to enable the bootloader by
connecting TX to RX, i.e. stick the connected PC in character echo
mode. Send a longish pseudo-random binary sequence out the TX and
expect it all back in the RX, if the same sequence is received switch
into bootloader mode. It's a pain because it requires you to run one
program to power up the board and another to interact with it
(minicom), but it may suit some.

regards,
Biff.

PS: Contact me off-list about any customisations.

[Petr Simandl]

Hi,
thanks for your fast response.
For us it seems to be the best option "hold button down
when you power on" to enter console menu.
I'll write you off-list.
thanks a lot and have a nice day
Petr