From owner-freebsd-hackers Fri Nov 7 19:55:45 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id TAA14310 for hackers-outgoing; Fri, 7 Nov 1997 19:55:45 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from ms11.hinet.net (root@ms11.hinet.net [168.95.4.11]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id TAA14304 for ; Fri, 7 Nov 1997 19:55:35 -0800 (PST) (envelope-from jwlo@ms11.hinet.net) Received: from ms11.hinet.net (dialup225.cyut.edu.tw [163.17.3.225]) by ms11.hinet.net (8.8.3/8.8.3) with ESMTP id LAA25075; Sat, 8 Nov 1997 11:56:35 +0800 (CST) Message-ID: <3463E1A7.DFFE15EB@ms11.hinet.net> Date: Sat, 08 Nov 1997 11:51:03 +0800 From: Doug Lo X-Mailer: Mozilla 4.03b8 [en] (X11; I; FreeBSD 2.2.5-RELEASE i386) MIME-Version: 1.0 To: Julian Elischer CC: freebsd-hackers@FreeBSD.ORG Subject: Re: Newest Pentium bug (fatal) References: <3463605C.41C67EA6@whistle.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk You wrote: > On a "genuine Intel" pentium (not pentium pro) > execution of the following sequence, 0xf0 0x0f 0xc7 0xc8 > > will stop the processor. This is doable from user mode and in > 16bitmode, or in fact any mode. > > try the following c program. > > unsigned char x[] = { 0xf0, 0x0f, 0xc7, 0xc8 }; > > main () > { > void (*f)(void) = x; > f(); > } > > We've checked: > K5... OK > P6... OK > P5... *SPLAT* > > no idea about the pentium II or other pentium copies. > K6? > > other pentium variants? > versions? > > this one DEFINITLY dies: > CPU: Pentium (99.38-MHz 586-class CPU) > Origin = "GenuineIntel" Id = 0x525 Stepping=5 > Features=0x1bf > Julian, I tried it. Also crashes. CPU: Pentium (132.96-MHz 586-class CPU) Origin = "GenuineIntel" Id = 0x526 Stepping=6 Features=0x1bf BTW, would anyone tell me what these arguments mean(0xf0, 0x0f, 0xc7, 0xc8)? Regards, Doug.