From owner-freebsd-arch Fri Jan 11 12: 8:46 2002 Delivered-To: freebsd-arch@freebsd.org Received: from ns.yogotech.com (ns.yogotech.com [206.127.123.66]) by hub.freebsd.org (Postfix) with ESMTP id 0D13F37B402 for ; Fri, 11 Jan 2002 12:08:35 -0800 (PST) Received: from caddis.yogotech.com (caddis.yogotech.com [206.127.123.130]) by ns.yogotech.com (8.9.3/8.9.3) with ESMTP id NAA28528; Fri, 11 Jan 2002 13:08:13 -0700 (MST) (envelope-from nate@yogotech.com) Received: (from nate@localhost) by caddis.yogotech.com (8.11.6/8.11.6) id g0BK8Dn11820; Fri, 11 Jan 2002 13:08:13 -0700 (MST) (envelope-from nate) From: Nate Williams MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15423.17965.472722.218250@caddis.yogotech.com> Date: Fri, 11 Jan 2002 13:08:13 -0700 To: Terry Lambert Cc: Bruce Evans , Nate Williams , Daniel Eischen , Dan Eischen , Peter Wemm , Archie Cobbs , Alfred Perlstein , arch@FreeBSD.ORG Subject: Re: Request for review: getcontext, setcontext, etc In-Reply-To: <3C3F455B.86856045@mindspring.com> References: <20020112054041.J3330-100000@gamplex.bde.org> <3C3F455B.86856045@mindspring.com> X-Mailer: VM 6.96 under 21.1 (patch 14) "Cuyahoga Valley" XEmacs Lucid Reply-To: nate@yogotech.com (Nate Williams) Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > > > > > > > Why is reporting a SIGFPE considered broken? This is a valid exception, > > > > > > > and it should be reported. > > > > > > > > > > > > Because the SIGFPE is for the broken context-switching code and not for > > > > > > the program. > > > > > > > > > > Ok, let's try again. How can I make sure that a SIGFPE that occur due > > > > > to a FPU operation is properly reported using fsave/frestor? > > > > > > > > The set of such proper reports is null, so it is easily generated by not > > > > using fsave (sic) or frstor. > > > > > > Huh? Are you saying that there are *NO* floating-point exceptions that > > > should be reported to a process? Doesn't posix require that exceptions > > > be thrown. > > > > I'm not saying any more, since I have made negative progress attempting > > to explain this. > > In other words, SIGFPE is about as trappable as SIGBUS or SIGILL, > and means about the same thing: an unrecoverable fault. It correctly works in single threaded programs in FreeBSD 2.2, but not in 4.4. > If you think about it a little, since you can't guarantee delivery > of signals to particular threads anyway, it makes sense that SIGFPE > would not be useful under any circumstances in threaded programs, > no matter how you sliced it. What Bruce is saying is that it's not possible to deliver the signal *AT ALL*, let alone in threaded programs. However, he contradicts his own statements in later parts of the same email, hence the confusion. Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message