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From: Vladimir Grebenschikov <vova@fbsd.ru>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
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Date: Mon, 20 Sep 2004 18:25:35 +0400
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Sender: Vladimir Grebenschikov <vova@vbook.fbsd.ru>
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Subject: Re: [HEADSUP] naming of tty devices.
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=F7 =D0=CE, 20/09/2004 =D7 15:51 +0200, Poul-Henning Kamp =D0=C9=DB=C5=D4:
> In message <414EDF66.8030907@cronyx.ru>, Roman Kurakin writes:
>=20
> >>>   Why not to add some general device enumeration for all devices,=20
> >>>especially
> >>>if devices would behave the same?
> >>>
> >>>tty%{global_port}
> >>>cua%{global_port}
> >>
> >>This doesn't work.
> >>
> >>There _are_ differences between serial devices and for instance
> >>PTYs or NMDM devices have very particular semantics.
> >>
> >but all tty devices have some generic abilities and behaviour, right?
> >(Sorry, I am a bit sio-centric, I didn't ever look inside ptys.)
>=20
> Yes, and those generic abilities is why I want systematic naming.
>=20
> But a global numbering gives you no way to know that tty234 is a PTY
> and tty235 is a USB device.

As da3 do not give you any hint is it SCSI disk, USB connected memory
card or firewire-connected DV-Camera.

I am not vote for uniform ttys numbering, just notice about similar
subsystem.

Actual another problem - ttys should be allocated from userland as
minimum tty/pty (in contrary with disks).

One of possible solutions - different dev name-spaces=20
/dev/tty/ZXX  - for generic ttys (all other ttys mapped there too)
/dev/pty/XX   - for pseudo-ttys
/dev/sio/XX   - for former ttydX
/dev/cua/XX   - for former cuaaX
/dev/nmdm/XX  - for null-modem
/dev/con/XX   - for console
etc...=20

But this layout broke any possible compatibility and will only confuse
userland (what name should be considered as primary ?)

I like pkh@ idea if there still way to list all available tty devices in
system. (sysctl or dev entry/directory)=20


--=20
Vladimir B. Grebenchikov
vova@fbsd.ru