Re: strange behaviour with /sbin/init and serial console

From: Ed Schouten <ed_at_80386.nl>
Date: Fri, 31 Oct 2008 20:06:14 +0100
Hello Theirry,

* Thierry Herbelot <thierry.herbelot_at_free.fr> wrote:
> with the following patch on /sbin/init, I have two different behaviours 
> depending on the console type (on a i386/32 PC) :
> - on a video console, I see the expected two messages,
> - on a serial console, the messages are not displayed (init silently finishes 
> its job and gets to start /etc/rc and everything)
> 
> I assume that the writev system call is implemented in 
> src/sys/kern/tty_cons.c::cnwrite(), but I could not parse the code to find an 
> explanation.
> 
> 	any taker ?
> 
> 	TfH
> 
> PS : this is initially for a RELENG_6 machine, but the code is quite similar 
> under RELENG_7 or Current

Any data written to /dev/console is not multiplexed to all console
devices, but only the first active device in the list. The reason behind
this, is because it adds a real lot of complexity to the console code,
especially related to polling and reading on /dev/console.

This weekend I'm going to commit a replacement implementation of
/dev/console, which also has this restriction.

-- 
 Ed Schouten <ed_at_80386.nl>
 WWW: http://80386.nl/

Received on Fri Oct 31 2008 - 18:06:15 UTC

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