Date: Tue, 26 Jan 2010 02:13:06 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: William Hubbs <w.d.hubbs@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, gregkh@suse.de,
       Samuel Thibault <samuel.thibault@ens-lyon.org>,
       Chris Brannon <cmbrannon79@gmail.com>, Kirk Reiser <kirk@reisers.ca>
Subject: Re: request for assistance:  accessing ttys from kernel space
Message-ID: <20100126021306.16809e71@lxorguk.ukuu.org.uk>
In-Reply-To: <20100126020203.GA23551@linux1>
References: <20100126020203.GA23551@linux1>
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> Currently, speakup is using direct hardware access to communicate with
> serial ports.  Doing so, however, has limitations since we are hard
> coding port addresses and IRQ numbers.  For example, we have a user

I pointed this out several years ago

> What I would like to discuss is how we can access ttys from kernel
> space.  If we could do this, it would definitely make things much easier
> for us in speakup.

Basically - use a line discipline, that lets you sit on top of a tty and
interact with the hardware

> We need to be able to access the ttys as early as possible in the boot
> sequence.  Any help, suggestions, or guidance you could give us would be
> greatly appreciated.

We may need to make some special provision for that aspect - we already
do so for the early serial console support. The ldisc is the start point
then there may be some bits that need to be extended around it.

A bigger problem is going to be the fact non USB serial is vanishing bit
by bit. We do have a USB console but it's truely crazy stuff and
extending it scares me 8)
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