From owner-freebsd-arch Fri Jan 11 14:56:48 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 57CB537B400 for ; Fri, 11 Jan 2002 14:56:37 -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 PAA05238; Fri, 11 Jan 2002 15:56:32 -0700 (MST) (envelope-from nate@yogotech.com) Received: (from nate@localhost) by caddis.yogotech.com (8.11.6/8.11.6) id g0BMuVa14300; Fri, 11 Jan 2002 15:56:31 -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: <15423.28063.92751.501022@caddis.yogotech.com> Date: Fri, 11 Jan 2002 15:56:31 -0700 To: Bakul Shah Cc: Terry Lambert , Dan Eischen , arch@FreeBSD.ORG Subject: Re: Request for review: getcontext, setcontext, etc In-Reply-To: <200201112251.RAA07625@repulse.cnchost.com> References: <3C3F690B.9A5959A1@mindspring.com> <200201112251.RAA07625@repulse.cnchost.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 > > > I am not prepared to speculate on the use of FP & SSE > > > registers at this point except for one thing: an FP exception > > > *must* be delivered to whichever thread caused it. Any bugs > > > in SIGFPE delivery is a separate discussion! > > [ ... ] > > > > Cool. We are all in agreement on this: the thread that > > caused it is the thread that executes an FPU instruction > > after an error in an instruction by some FPU using thread, > > whatever thread that is. > > > > 8-p > > > > The exception signalling lags the event that was the cause > > of the exception in x86 hardware, if this wasn't clear... > > What is not clear to me is why is this relevant only now -- > whether the kernel switches threads or they are switched in > the user mode, the bug (if there is one) will bite you the > same, right? Explain it real slowly. :-) It's not any more/less relevant now. It's just that it was mostly misunderstood in the past, and since we're trying to make get/setcontext library calls, we want to make sure to get it right. According to Bruce, it may not work as we expected in the past. > I'd better readup on x86 FP.... Hopefully you're reading will be better than mine. :( Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message