*BSD News Article 77497


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From: richw@yank.kitchener.on.ca (Rich Wales)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: 2.1.5-RELEASE sio silo overflows?
Date: 5 Sep 1996 11:02:18 -0400
Organization: Opinions expressed in this posting are mine alone
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Message-ID: <19960905145725.richw@yank.kitchener.on.ca>
References: <50i54c$mq7@yama.mcc.ac.uk> <50kb48$9ok@helena.MT.net>
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"Nate Williams" <nate@sneezy.sri.com> wrote:

	This is a 'known problem' with 2.1.5R.  Basically, Bruce
	modified the driver to actually *report* overflows that
	weren't being reported in previous versions of FreeBSD.
	The solution is to either ignore them (I've been doing
	this), or modify sio.c to set the trigger level from 14
	to 8 in the sources which should remove them at some
	interrupt cost.

Perhaps one or more "flags" bits could be used to specify the trigger
level.  BSD/OS 2.x does it this way, for example; four high-end "flags"
bits (in the 0xf00000 range) are used to specify receive trigger level,
output FIFO size, and hardware flow control.

Using "flags" bits in FreeBSD would also allow the settings to be cus-
tomized without having to recompile the kernel.

Rich Wales <richw@yank.kitchener.on.ca>
http://yank.kitchener.on.ca/~richw/