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Date: Fri, 31 Oct 2008 20:06:14 +0100
From: Ed Schouten <ed@80386.nl>
To: Thierry Herbelot <thierry.herbelot@free.fr>
Message-ID: <20081031190614.GQ1165@hoeg.nl>
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Cc: hackers@freebsd.org, current ML <current@freebsd.org>
Subject: Re: strange behaviour with /sbin/init and serial console
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Hello Theirry,

* Thierry Herbelot <thierry.herbelot@free.fr> wrote:
> with the following patch on /sbin/init, I have two different behaviours=
=20
> 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 fini=
shes=20
> its job and gets to start /etc/rc and everything)
>=20
> I assume that the writev system call is implemented in=20
> src/sys/kern/tty_cons.c::cnwrite(), but I could not parse the code to fin=
d an=20
> explanation.
>=20
> 	any taker ?
>=20
> 	TfH
>=20
> PS : this is initially for a RELENG_6 machine, but the code is quite simi=
lar=20
> 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.

--=20
 Ed Schouten <ed@80386.nl>
 WWW: http://80386.nl/

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