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To: Bruce Evans <bde@zeta.org.au>
cc: bde@freebsd.org, bugs@freebsd.org, hackers@freebsd.org, jmz@freebsd.org
Subject: Re: modloaded block/char device drivers 
In-reply-to: Your message of "Fri, 22 Mar 1996 23:58:50 +1100."
             <199603221258.XAA05969@godzilla.zeta.org.au> 
Date: Fri, 22 Mar 1996 09:34:36 -0800
From: Paul Traina <pst@shockwave.com>
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  From: Bruce Evans <bde@zeta.org.au>
  Subject: Re: modloaded block/char device drivers
  
  qcam should also worry about conflicts with lpt* :-).  Someone might
  even want to use the same lpt port at different times for printing,
  parallel port TCP/IP, and qcam.  The lpt driver and the plip driver are
  in the same file so that they can be selected between using an ioctl.
  There's gotta be a better way to do this.

Yep.  Right now, they actually /do/ stay out of each others way, as long
as you don't try to open both devices at the same time.

It seems to me, we need something like a top half and a bottom half of
the kdc, the top half stays with the driver (i.e. belongs to qcam or lpt)
and the bottom half stays with the hardware.  Then opening either device
would lock out the other device.