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Date: Tue, 8 Jan 2002 16:58:51 -0500
From: "Michael H. Warfield" <mhw@wittsend.com>
To: Andrew Morton <akpm@zip.com.au>
Cc: David Weinehall <tao@acc.umu.se>, Richard Gooch <rgooch@ras.ucalgary.ca>,
        Ivan Passos <ivan@cyclades.com>, linux-kernel@vger.kernel.org
Subject: Re: Serial Driver Name Question (kernels 2.4.x)
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On Mon, Jan 07, 2002 at 10:23:04PM -0800, Andrew Morton wrote:
> David Weinehall wrote:
> > 
> > On Mon, Jan 07, 2002 at 09:03:35PM -0800, Andrew Morton wrote:
> > > [ tty driver name breakage ]
> > >
> > > Richard, can we please get this wrapped up?
> > >
> > > My preferred approach is to change the driver naming scheme
> > > so that we don't have to put printf control-strings everywhere.
> > > We can remove a number of ifdefs that way.
> > 
> > Wouldn't it be cleaner to have:
> > 
> > #ifdef CONFIG_DEVFS_FS
> >         serial_driver.name = "tts/";
> > #else
> >         serial_driver.name = "tts";
> > #endif
> > 
> > and
> > 
> >         sprintf("buf, "%s%d", name, idx + tty->driver.name_base);
> > 
> > respectively?!
> > 

> Well, with the scheme I proposed most drivers won't need the
> ifdef.  It'll just be:

> 	serial_driver.name = "cua";

> With devfs enabled that expands to cua/42.  Without devfs it expands
> to cua42.

	No.

	We've been over this in several lists and there are more
issues here.  The Computone driver is ttyF%d / tts/F%d cuf%d / cua/F%d.
If I understand your convention (and maybe I do not) then the cuf
driver would be what?  Expanded to cuf/42 with devfs and cuf42 without?
That's what it use to be and that created a problem in userland.  The
trouble there is the problem with conventional lock files under
/var/lock which only use the base name of the device name so cua/42
and cuf/42 both have the same lock file of /var/lock/LCK..42 and
would collide.  Yes we could ALSO change ALL the user space applications
using locks, but I just got done changing the Computone driver to conform
to the non-conflicting convention that had been agreed to.  This also
impacts the USB ACM driver and it's devices and lock files.

	Unfortunately, the basenames need to be non-conflicting in flat
name space due the the indeterminant pile of applications which are going
to require non-conflicing lock files under a convention that days back to
before Linux or even Taylor UUCP (HDB UUCP used a similar locking scheme).
That includes pppd, slip, uucp, minicom, cu, ecu, tip, mgetty, etc, etc...

> Seems that some drivers have had their name changed when used under
> devfs (tts/%d versus ttyS%d).  But a lot have not.

	Other drivers which are not under ttyS%d don't make to tts/%d.
As things stand right now, ttyF%d maps to tts/F%d.  It use to be mapped
under ttf/%d but this created a lock file conflict with the tts/%d and
usb/acm/%d devices and had to be changed.

> -
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	Mike
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