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From: simon@its63b.ed.ac.uk (Simon Brown)
Newsgroups: comp.unix.wizards
Subject: Re: No more signals
Message-ID: <490@its63b.ed.ac.uk>
Date: Sun, 21-Jun-87 17:45:19 EDT
Article-I.D.: its63b.490
Posted: Sun Jun 21 17:45:19 1987
Date-Received: Fri, 26-Jun-87 03:44:25 EDT
References: <48300005@hcx1>
Reply-To: simon@its63b.ed.ac.uk (Simon Brown)
Organization: Computer Science Department, Edinburgh University
Lines: 36

In article <48300005@hcx1> tomp@hcx1.SSD.HARRIS.COM writes:
>
>I am trying to implement the SIGWINCH (window size change) signal and ran into
>an interesting problem: no more signals are left. Our kernel is a combination
>of both Berkeley and AT&T. Our machine has a 32 bit word size. The system keeps
>a mask of the signals and checks it in such places as system call entry/exit.
>I think that making up some sort of 64 bit structure to hold the mask would be 
>a performance hit because the signal mask is checked in critical places. The
>other solution is to overload an existing signal, but this isn't a general
>solution.
>
>Anyways, has anyone out there ran into (or even thought about) this problem. If
>so, I would like to get ideas about how this problem will be addressed in the
>future. It is going to affect everyone pretty soon as Berkeley only has one
>signal left (AT&T has about 8 left).

Of course, it's really only a problem because of the stupidity and short-
sightedness of both the BSD and AT&T people :-(. Under Version-7 one quickly
ran out of signals ('cos there were only 16 of them), and so when people started
implementing things on 32-bit machines, one would have thought that they would
have realized that this was a big problem that required a completely new way
of doing things, not just a case of "oh, well 16 wasn't enough, but I'm sure
that 32 will be!". For the same reason, going up to 64 is NOT a good solution
(though I'm sure that'll be what will happen).

	%{
	    Simon!
	%}

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| Simon Brown 		         | UUCP:  seismo!mcvax!ukc!its63b!simon
| Department of Computer Science | JANET: simon@uk.ac.ed.its63b
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