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Date: Mon, 15 Oct 2001 14:38:40 +0200
From: Jamie Lokier <lk@tantalophile.demon.co.uk>
To: Pavel Machek <pavel@suse.cz>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Jelson <jelson@circlemud.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [ANNOUNCE] FUSD v1.00: Framework for User-Space Devices
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Pavel Machek wrote:
> I do not think tty/pty pair does cut it for AT emulation. Can you
> really emulate all neccessary features using pty/tty?

Remember that if you go for a full user-space driver, you have to
duplicate the kernel's tty layer to emulate everything.  For full
compatibility, that means emulating all the ancient serial and tty
ioctls properly including Linux-specific ones, SYSV-style ones,
BSD-style ones etc.

That's already been done _and_ tested in the kernel over the years.
While repeating that in user space is possible, I suspect that a pty/tty
interface would end up providing better compatibility (in practice) for
all the different, special and ancient terminal programs.  In the cases
where pty/tty doesn't relay enough information to the pty side, we
should look at whether minor changes to the pty driver can fix that.

cheers,
-- Jamie
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