Subject: Re: TTY virtualization driver
To: NetBSD Kernel Technical Discussion List <tech-kern@NetBSD.ORG>
From: Greg A. Woods <>
List: tech-kern
Date: 01/22/2002 12:32:02
[ On , January 22, 2002 at 16:49:50 (-0000), wrote: ]
> Subject: Re: TTY virtualization driver
> serial port is run by one chip and some machines where it's run by another.
> So you never really know what device node corresponds to the port you just
> plugged your serial cable into.

Just as with disks the only real solution is to hard-wire your kernel
configuration so that you know what major/minor numbers correspond to
what hardware device(s).  Unfortunately unlike disks there's no way to
do this for serial ports without renaming files in /dev.

To this end a "virtualization" layer, i.e. a mid-level driver layer that
separates out the low-level serial port device drivers from the tty
layer, providing just one major number for all /dev/tty?? nodes (just as
the scsi drivers have a layer to separate out the 'sd' device from the
host adapter layer to allow just one major number to serve for all the
/dev/sd?? nodes) would be useful since then the person configuring the
kernel could hard-wire the tty?? assignments to specific devices without
having to rename anything in /dev (and edit /dev/MAKEDEV.local, etc.).

								Greg A. Woods

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