Date: Fri, 14 Nov 1997 22:58:44 -0800 (PST) From: Sean Eric Fagan <sef@kithrup.com> To: bugs@freebsd.org Subject: Re: Foof! bug fix? Message-ID: <199711150658.WAA22009@kithrup.com> In-Reply-To: <199711150535.VAA15414.kithrup.freebsd.bugs@implode.root.com> References: Your message of "Fri, 14 Nov 1997 17:57:37 MST." <3.0.5.32.19971114175737.00928b90@mail.lariat.org>
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In article <199711150535.VAA15414.kithrup.freebsd.bugs@implode.root.com> you write: > We're evaluating what looks to be a far superior (and simpler!) fix that >was proposed by Jonathan Lemon (a FreeBSD contributor). Again, we want the >"right" fix, not just the "right now" fix. I've appended Jonathan's proposal >to the end of the message in case you need something "right now". :-) It's important to realize that this "far superior (and simpiler!)" "fix" breaks existing practice and code. Specifically, it causes all illegal instructions to generate a SIGBUS, instead of the current SIGILL. Note that this means a program would behave differently on two different machines, running identical versions of the operating system -- unless, of course, illegal instructions are suddenly defined to always generate SIGBUS. This can be changed by having trap() identify faults which are due to illegal instructions, and which are other general protection faults. I wasn't able to see an easy way to do that, and I've expressed my concern to Jonathan. I think it unlikely that Intel did not think of this attempt; assuming they did, there is a very good reason that they did not give this as their official workaround.
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