Date: Fri, 11 Jan 2002 12:04:43 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Bruce Evans <bde@zeta.org.au> Cc: Nate Williams <nate@yogotech.com>, Daniel Eischen <eischen@pcnet1.pcnet.com>, Dan Eischen <eischen@vigrid.com>, Peter Wemm <peter@wemm.org>, Archie Cobbs <archie@dellroad.org>, Alfred Perlstein <bright@mu.org>, arch@FreeBSD.ORG Subject: Re: Request for review: getcontext, setcontext, etc Message-ID: <3C3F455B.86856045@mindspring.com> References: <20020112054041.J3330-100000@gamplex.bde.org>
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Bruce Evans wrote: > On Fri, 11 Jan 2002, Nate Williams wrote: > > > > > > 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. 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. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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