Date: Mon, 27 Jan 1997 15:44:19 -0700 (MST) From: Don Yuniskis <dgy@rtd.com> To: Shimon@i-Connect.Net (Simon Shapiro) Cc: dgy@rtd.com, freebsd-hackers@freefall.freebsd.org, bde@zeta.org.au Subject: Re: suggestion for kernel printk() ? Message-ID: <199701272244.PAA15452@seagull.rtd.com> In-Reply-To: <XFMail.970127153007.Shimon@i-Connect.Net> from "Simon Shapiro" at Jan 27, 97 02:23:10 pm
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It seems that Simon Shapiro said:
> > > > I just spent some time fighting a kernel that died miserably
> > > >on boot :-( I was inundated with an endless stream of kernel
> > > >messages (in highlighted text) followed promptly by a hard reset.
> > > >It was quite frustrating to find that there doesn't seem to be a
> > > >mechanism to pause the display at this point!
> >
> > However, is it worthwhile for the mechanism that printk() ?? uses to
> > observe some kind of flow control? It did not recognize scroll_lock,
> > pause, ^S, etc. This would have at least enabled me to read some
> > (i.e. one screen full) of the messages to see what the kernel was
> > complaining about.
>
> I may be offbase here, but scroll-lock, etc. are INPUT, while printk is
Yes. But all of those mechanisms tie in to provide flow control for
regular console output functions. Apparently, however, this happens
at a higher level than I had hoped/assumed (i.e. more stuff has to be
functional before this mechanism works).
> output. No? Maybe a (oops :-) SysV-like mechanism where print{kf} go to
> a circular buffer andanother mechanism dumps it to ``the console''.
> If you like ugly, (if memory serves), you can either pass an additional arg
> to the output routine (A la Linux) or designate the first character in the
> string to tell what to do, as in ~==console and buffer, !=bufferonly, etc.
I was suggesting having printk() examine the keyboard buffer for a pending
"pause" key and blocking in this event. However, it appears that the
system couldn't handle that crude of an implementation...
--don
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