*BSD News Article 6051


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Newsgroups: comp.unix.bsd
Path: sserve!manuel!munnari.oz.au!uunet!haven.umd.edu!darwin.sura.net!Sirius.dfn.de!news.uni-stuttgart.de!news.uni-stuttgart.de!nils
From: nils@merlin.ims.uni-stuttgart.de (Cornelis van der Laan)
Subject: Re: [386BSD] can FIFO support be made to work?
In-Reply-To: scott@lopez.marquette.MI.US's message of Tue, 29 Sep 1992 01:55:43 EDT
Message-ID: <NILS.92Oct5125819@merlin.ims.uni-stuttgart.de>
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Reply-To: nils@ims.uni-stuttgart.de
Organization: IMS, University of Stuttgart, Germany
References: <Tzyle-iA1@lopez.marquette.MI.US>
Distribution:  world
Date: Mon, 5 Oct 1992 11:49:55 GMT
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>>>>> On Tue, 29 Sep 1992 01:55:43 EDT, scott@lopez.marquette.MI.US (Scott Reynolds,Insanity) said:

Scott> I've added the necessary "options FIFO" to my configuration and done the
Scott> config, and I had to modify the .depend file manually to make sure that
Scott> the proper fifo.h file was picked up.  This was no real problem, and I

Be sure to not include an 'pseudo-device fifo' line in the config file
and remove any left over fifo.h in /sys/compile/You-Kernel. It is not
needed and is included before the correct /sys/sys/fifo.h. Then remove
all your kernel .o files and - after a make depend which should rebuild
the dependancy file correctly now - rebuild your kernel.

Scott> rebooted and made a fifo only to discover that opening the fifo for writing
Scott> caused the tty to hang.

Doesn't happen to me on 386BSD; but if someone writes some characters to a
fifo that no one has open for reading, all characters are lost. 
On a sun instead the writing process hangs until a reader opens the fifo;
no input gets lost.
I don't know the semantics of fifos. Which one is correct ? 

-- Nils.