Re: parport patch / lp_readback

Martin Buck (
Thu, 24 Apr 97 19:36 CDT

> The problem with the printer device (at the moment) is that you can open it
> once, not twice or multiple times. The best way for a status monitor or
> whatever is to use a modified printer daemon like LPRng. This daemon handles
> all reads and writes from and to lp.

I was thinking about a daemon that creates a named pipe in /dev that can be
used by lpd (or any other program that wants to access the printer) to send
the data to the printer. The only problem with this approach: programs
using the named pipe don't know anything about the status of the printer,
because the errnos for "out of paper" and the like can't be sent through a
pipe. :-(

I'll have a look at LPRng to see if it makes this task easier.

> As you see, we are polling inside the driver, but this is the only
> possiblity to wait without interrupt configured.

Is the nibble mode able to use interrupts if the printer device is
configured for interrupts?


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