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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.bugs.4bsd
Subject: Re: Question about 4.2BSD uprintf()
Message-ID: <3326@umcp-cs.UUCP>
Date: Sat, 22-Feb-86 14:31:11 EST
Article-I.D.: umcp-cs.3326
Posted: Sat Feb 22 14:31:11 1986
Date-Received: Mon, 24-Feb-86 20:54:29 EST
References: <559@stride.stride.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 22

In article <559@stride.stride.UUCP> bruce@stride.UUCP (Bruce Robertson)
writes:

> The comments for the function uprintf() advertise that you can
> call it from an interrupt routine to send a message to the
> current user's terminal.  [But] uprintf() will print its message
> on the terminal of the *currently running* process.

Right you are.

> I can't think of any situation where you would want to actually
> call uprintf() from an interrupt routine.

Messages like `no write ring', while they do not really belong in
the kernel, are useful; these can be done by noting the lack of a
write ring in some per-device data structure, and having the device
open routine do the uprintf() as well as returning an error.  (Some
tape drives do not have write lock as a status bit: you must ask.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1415)
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