Re: Serial Driver Name Question (kernels 2.4.x)

Michael H. Warfield
2002-01-08T21:59:36Z

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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