From owner-freebsd-hardware Wed Jan 9 5: 6: 2 2002 Delivered-To: freebsd-hardware@freebsd.org Received: from mcqueen.wolfsburg.de (pns.wobline.de [212.68.68.5]) by hub.freebsd.org (Postfix) with ESMTP id D318D37B405 for ; Wed, 9 Jan 2002 05:05:53 -0800 (PST) Received: from colt.ncptiddische.net (ppp-151.wobline.de [212.68.69.159]) by mcqueen.wolfsburg.de (8.11.3/8.11.3/tw-20010821) with ESMTP id g09D5jn07133 for ; Wed, 9 Jan 2002 14:05:46 +0100 Received: from tisys.org (jodie.ncptiddische.net [192.168.0.2]) by colt.ncptiddische.net (8.11.6/8.11.6) with ESMTP id g09D6gX48874 for ; Wed, 9 Jan 2002 14:06:43 +0100 (CET) (envelope-from nils@tisys.org) Received: (from nils@localhost) by tisys.org (8.11.6/8.11.6) id g09D60e68798 for freebsd-hardware@freebsd.org; Wed, 9 Jan 2002 14:06:00 +0100 (CET) (envelope-from nils) Date: Wed, 9 Jan 2002 14:05:25 +0100 From: Nils Holland To: freebsd-hardware@freebsd.org Subject: PCI Interrupt Sharing Message-ID: <20020109140525.A68773@tisys.org> Mail-Followup-To: freebsd-hardware@freebsd.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i X-Operating-System: FreeBSD jodie.ncptiddische.net 4.5-PRERELEASE FreeBSD 4.5-PRERELEASE X-Machine-Uptime: 1:57PM up 1:40, 1 user, load averages: 0.00, 0.00, 0.03 Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Hi folks, the following is not really a FreeBSD specific question, but I thought I might ask it anyway and see if someone can give me an answer. So, on my machine, I have the BIOS assign IRQs to my PCI devices automatically (in fact, I only have PCI devices in use). When I look at the resource allocation (dmesg.boot below), I notice that two cards (pci1 and ed0) share the same IRQ (11). I've also noticed that if I enable my on-board USB controller, it will get IRQ 10 assigned, which means that it would share an IRQ with bktr0 (the USB controller is not visible in the dmesg.boot below since I don't use any USB devices and disabled it). Basically, from what I have read, IRQ sharing is normal for PCI devices, and thus is not something to worry about, except probably if trouble occurs. On my system, however, I have never had any problems the way it is set up right now. Still, I wonder if it would make some difference in terms of performance (or whatever) if I manually made sure in the BIOS that every IRQ is only used once. So, do you think I should simply leave everything as it it ("If it ain't broken, don't fix it"), or do you think that for some reasons I should manually get rid of PCI devices sharing IRQs? I'm a little curious about this, so any hints are welcome! Greetings Nils Copyright (c) 1992-2002 The FreeBSD Project. Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 The Regents of the University of California. All rights reserved. FreeBSD 4.5-PRERELEASE #0: Sat Jan 5 11:41:47 CET 2002 root@poison.ncptiddische.net:/usr/obj/usr/src/sys/JODIE Timecounter "i8254" frequency 1193182 Hz Timecounter "TSC" frequency 996634437 Hz CPU: AMD Athlon(tm) processor (996.63-MHz 686-class CPU) Origin = "AuthenticAMD" Id = 0x642 Stepping = 2 Features=0x183f9ff AMD Features=0xc0440000<,AMIE,DSP,3DNow!> real memory = 805240832 (786368K bytes) avail memory = 779370496 (761104K bytes) Preloaded elf kernel "kernel" at 0xc0367000. Pentium Pro MTRR support enabled Using $PIR table, 8 entries at 0xc00fdba0 npx0: on motherboard npx0: INT 16 interface pcib0: on motherboard pci0: on pcib0 pcib1: at device 1.0 on pci0 pci1: on pcib1 pci1: at 0.0 irq 11 isab0: at device 7.0 on pci0 isa0: on isab0 atapci0: port 0xd000-0xd00f at device 7.1 on pci0 atapci0: Correcting VIA config for southbridge data corruption bug ata0: at 0x1f0 irq 14 on atapci0 ata1: at 0x170 irq 15 on atapci0 chip1: at device 7.4 on pci0 pcm0: port 0xe400-0xe403,0xe000-0xe003,0xdc00-0xdcff irq 5 at device 7.5 on pci0 bktr0: mem 0xdc001000-0xdc001fff irq 10 at device 16.0 on pci0 iicbb0: on bti2c0 iicbus0: on iicbb0 master-only smbus0: on bti2c0 bktr0: Hauppauge Model 44354 C221 bktr0: Detected a MSP3415D-B3 at 0x80 bktr0: Hauppauge WinCast/TV, Philips FR1216 PAL FM tuner, msp3400c stereo, remote control. pci0: (vendor=0x109e, dev=0x0878) at 16.1 irq 10 ed0: port 0xe800-0xe81f irq 11 at device 17.0 on pci0 ed0: address 00:20:18:2f:42:2d, type NE2000 (16 bit) orm0: