[term] No echo output on serial port when using lua and panic_kb

[aenrbes]

Hi @vvaltchev

When boot tilck with "-sercon" (whether it's riscv64 or i386), lua and panic_kb can read serial input, but there is no echo on the serial port.
I think the reason for this problem may have something to do with some of the presupposition of the tty subsystem, but this part code is a little complicated for me to understand at the moment.

lua works, it can read comand (print("hello!")) from serial input, but no echo on serial port

same problem using cat

I've observed so far that serial port is treated differently, at least in the tty_keypress_echo function:

static void tty_keypress_echo(struct tty *t, char c)
{
   struct termios *const c_term = &t->c_term;

   if (t->serial_port_fwd)
      return;

...
}

[vvaltchev]

Thanks for reporting this. I agree that it has nothing to do with RISCV.