I want to make a dialogue with user at the beginning of boot, I decided to do it in /etc/init.d/rcS as I don't know a better way... but the phone dies very quickly when trapped in a dialogue... no more than 20 seconds to get all
So tell me please, what the poser?

Find the thread on Recovery Console.

Then look at my directions for adding shell-access early at boot. Part of that code (it's explained through-out posts preceding my tutorial) deals with what you need to stop the watchdogs from rebooting the device.

For now though, if you can't get past the dialog and boot all the way because of this, use flasher to set R&D Mode to on and the no-watchdog flags to on, so that you can boot up once to get to that point.

Thank you very much!

// went looking for your post

Just enable RD mode, it's really annoying to have the phone reboot "just because" it's swapping out the wrong pages.

True, but that requires the no-lifeguard-reset flag to be set too. (No harm in that, just saying though.)

Also, R&D mode will cause your keyboard to flicker annoyingly/awesomely (depending on taste) in display of system activity, thus eating more battery. Disabling this requires commenting out a line (or two) in /sbin/preinit.

Either way, some people might want to know how to disable watchdogs, without enabling R&D mode.

just this lines
---
modprobe omap_wdt
modprobe twl4030_wdt
sleep 1
for p in /sys/bus/platform/devices/*_wdt/misc:*; do
n=`basename $p | sed "s/.*://"`
rm -f /dev/$n
mknod /dev/$n c `cat $p/dev | sed "s/:/ /g"`
done
watchdogs
killall watchdogs
---
doesn't stop reboots
is the "for" loop was necessary?..

and I had two "Unexpected close, watchdog still running"
but this is not with 'sh'

Your problem is either...

1: You didn't read the full how-to - you need to have "watchdogs", i.e. download the bootmenu .deb file and extract the watchdogs binary out of there (or if you already have bootmenu, you already have the 'watchdogs' command, so skip this).

...and/or...

2: If you're using the code above, that means you're literally running "killall watchdogs" right after "watchdogs". This is a problem because watchdogs is the process that, after you launch it, keeps kicking the watchdogs so that they don't spontaneously reboot. You don't want to kill it immediately after launching it.

So put your code (the one that creates the dialog to interact with the user at boot), in between "watchdogs" and "killall watchdogs". (Note how in my approach the command "sh" is between watchdogs and "killall watchdogs" - this is so that watchdogs is launched right before giving the user a shell, and killall watchdogs doesn't run until after the user has exited the shell.)

Hope that helps.

yes, my problem was "2" ^). And I just replaced sh-call with "pwd=`sh -c 'read pwd; echo $pwd'` "... not so much a dialog as a "dialog"
---
watchdogs
echo "Enter PIN"
pwd=`sh -c 'read pwd; echo $pwd'`
killall watchdogs
---