Re: serial console unplugged, boot hangs, help !

[Jason Wright <jason@thought.net>]

> Richard Bignell writes:
> 
>  > nothing else happens on the VGA screen. Great, ...but... I checked 
>  > what happens if the terminal (minicom on Linux in my case) is 
>  > unplugged at boot time, and the boot process *hangs* !! When I plug 
> 
> Guess: the software is looking for `carrier' which is gone when the
> term is unplugged.  If that is the problem and you can't get around
> it in software you can always make a plug that ties CTS to RTS and
> DTR to DCD and DSR to make things happy.
> 
I was just looking into this the other day (with mickey's guidance).
OpenBSD uses BIOS calls for serial console in the boot program.  These
calls will block forever waiting for the transmit of the first character
(they never seem to timeout, even though the bios has a mechnanism for
returning this fact), presumably waiting on carrier.  One you get past the
bios calls and the kernel itself is controlling the serial port,
everything works fine.

To get around this, we'd need a real com driver in 'boot', which we used
to have, but it didn't work with all computers (at least that's my
understanding).

--Jason Wright