From owner-freebsd-smp Tue Feb 9 10:30:50 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA19115 for freebsd-smp-outgoing; Tue, 9 Feb 1999 10:30:50 -0800 (PST) (envelope-from owner-freebsd-smp@FreeBSD.ORG) Received: from cannon.ma.ikos.com (cannon.ma.ikos.com [137.103.105.19]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id KAA19107 for ; Tue, 9 Feb 1999 10:30:48 -0800 (PST) (envelope-from tich@cannon.ma.ikos.com) Received: from lonesome.ma.ikos.com (lonesome [137.103.105.44]) by cannon.ma.ikos.com (8.9.1/8.8.8) with ESMTP id NAA02369; Tue, 9 Feb 1999 13:31:56 -0500 (EST) From: Richard Cownie Received: (from tich@localhost) by lonesome.ma.ikos.com (8.8.8/8.8.8) id NAA24011; Tue, 9 Feb 1999 13:31:56 -0500 (EST) Date: Tue, 9 Feb 1999 13:31:56 -0500 (EST) Message-Id: <199902091831.NAA24011@lonesome.ma.ikos.com> To: Thierry.Herbelot@alcatel.fr, smp@FreeBSD.ORG Subject: Re: Mixing P2 Types Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org With the PentiumPro it was definitely true that all CPU's in an SMP system had to be identical (same speed, same silicon stepping) - one particular problem that would occur if you violated this was that the cpu's would come out of reset and start their APIC bus negotiation at different times, resulting in more than one cpu acting as the Boot CPU and attempting to run the BIOS; this would usually cause severe confusion. There may be other problems as well. Since nothing much has changed in the bus architecture, boot protocol, or indeed the CPU core between PentiumPro and Pentium-II, I believe it's probably still true that all cpu's in an SMP system must be identical. Not to say that a mixed-CPU system won't work at all - but it isn't guaranteed to work, and it probably won't work reliably. In my former incarnation at Axil Computer, I had to write the diagnostic code that would allow us to check the silicon stepping info of each CPU in an 8-way SMP NX801 to detect any mismatches. Believe me, I wouldn't have done this if it wasn't a problem ... Regards Richard Cownie (tich@ma.ikos.com) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message