From owner-freebsd-smp Mon May 1 11:15:17 2000 Delivered-To: freebsd-smp@freebsd.org Received: from gndrsh.dnsmgr.net (GndRsh.dnsmgr.net [198.145.92.4]) by hub.freebsd.org (Postfix) with ESMTP id A632837CB84 for ; Mon, 1 May 2000 11:15:11 -0700 (PDT) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: (from freebsd@localhost) by gndrsh.dnsmgr.net (8.9.3/8.9.3) id LAA01684; Mon, 1 May 2000 11:14:39 -0700 (PDT) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <200005011814.LAA01684@gndrsh.dnsmgr.net> Subject: Re: hlt instructions and temperature issues In-Reply-To: <00043018413807.18195@kyxbot.zorg> from Dragos Ruiu at "Apr 30, 2000 06:36:46 pm" To: dr@dursec.com (Dragos Ruiu) Date: Mon, 1 May 2000 11:14:39 -0700 (PDT) Cc: kpielorz@tdx.co.uk (Karl Pielorz), djb@ifa.au.dk, smp@csn.net (Steve Passe), smp@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > On Sun, 30 Apr 2000, Karl Pielorz wrote: > > Taking it to an extreme, it would be like building a system that falls over > > when it 'happens to be busy' one day, 'cause someone ran something > > computationally intensive? - I know for a fact these systems do exist, but we > > don't really want to be helping sweep the cause under the rug do we? > > > > > Tell that to IBM... one of the famous stories from classic computing > history is the mainframe they built with the HCF opcode. > Halt and Catch Fire. It turned out that for this model > you could lock up into a tight one instruction loop and > the CPU core would overheat and literally smoke. > > It's documented in the ancient back issues Mr. Neuman's > old Risks usenet newsgroup in the early eighties. Right along with the chain breaking/hammer bank smoking code for the 1403 printers.... basically a very specific sequence of lines with very special character sequences could cause 1/3 of the hammer bank to fire every 14uS or so, do that for more than 10 cycles or so and you could litterly break the print character chain. De-optimize it for chain breaking and run it for 10 minutes and you would start smoking the hammer coils.... -- Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message