From owner-freebsd-smp Mon Aug 11 23:31:50 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id XAA03661 for smp-outgoing; Mon, 11 Aug 1997 23:31:50 -0700 (PDT) Received: from scorpion.aracnet.com (root@scorpion.aracnet.com [205.159.88.23]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id XAA03535 for ; Mon, 11 Aug 1997 23:27:46 -0700 (PDT) Received: from cbrowni2-home (ppp-h2.aracnet.com [205.238.12.195]) by scorpion.aracnet.com (8.8.5/8.8.5) with ESMTP id XAA07185 for ; Mon, 11 Aug 1997 23:26:49 -0700 Message-ID: <33F0021F.49BFE86@earthling.net> Date: Mon, 11 Aug 1997 23:26:39 -0700 From: Chris Browning Reply-To: cbrown@aracnet.com X-Mailer: Mozilla 4.01 [en] (WinNT; I) MIME-Version: 1.0 To: smp@FreeBSD.ORG Subject: Re: General smp & bios questions X-Priority: 3 (Normal) References: <199708120359.VAA17290@Ilsa.StevesCafe.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > > My system has to I/O APIC's in it. The 2nd one is disabled > > by default in the bios. yeah, disabling the second I/O APIC is a pretty normal default. Some brain-dead OSes can't handle more than one. > > I also have an entry for 'PIC interrupt Routing', which is > > set to 'default'. The other choice is 'Through IO APIC'. Using the "Through IO APIC" allows the I/O APIC to deliever interrupts through the APIC bus. This is the prefered way of doing things. Otherwise, interrupts are "hardwired" to a particular processor. It doesn't matter too much since when the system is put into full SMP mode, you will leave whichever one you choose. Through the I/O APIC is closer to SMP :-). > > > > Does any of this ring any bells? Yes. I work with our BIOS group to help them use these features. > I've left the 2nd APIC disabled > > since I did not beleive that your code supported more than one > > of them. Now, this would be a shame. This is a major scalibility limiter. If possible, you should use the 2nd I/O APIC. Otherwise, you are losing several interrupts and are crowding the ISA compatibility interrupts unecessarily. > leave the second APIC disabled, and use "Through IO APIC" Any particular reason why? All of those extra interupts going to waste? I agree with the "Through IO APIC". Chris Not speaking for nobody.