From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pz0-f52.google.com ([209.85.210.52]:35955 "EHLO mail-pz0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890Ab2DPQCo (ORCPT ); Mon, 16 Apr 2012 12:02:44 -0400 Received: by dake40 with SMTP id e40so7099736dak.11 for ; Mon, 16 Apr 2012 09:02:44 -0700 (PDT) Subject: pci_check_type2() help. From: Onkar N Mahajan To: linux-pci@vger.kernel.org Content-Type: text/plain; charset="ISO-8859-15" Date: Mon, 16 Apr 2012 21:32:40 +0530 Message-ID: <1334592160.26350.13.camel@oc4748611672.ibm.com> Mime-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org List-ID: Hello list, I am trying to understand the PCI functionality in Linux kernel. What is the best way to start to understanding this - where to start in the kernel code ? Books ? Manuals ? I started reading the code - where I am stuck in this function - pci_check_type2() ; Wherein I am not able to get from where these values 0xCFB,0xCF8,0xCFA are arrived at ? I guess these are port numbers , but in which manuals can I find this all information. linux/arch/x86/pci/init.c: static int __init pci_check_type2(void) { unsigned long flags; int works = 0; local_irq_save(flags); outb(0x00, 0xCFB); outb(0x00, 0xCF8); outb(0x00, 0xCFA); if (inb(0xCF8) == 0x00 && inb(0xCFA) == 0x00 && pci_sanity_check(&pci_direct_conf2)) { works = 1; } local_irq_restore(flags); return works; } Please help me figuring out right manuals for this. -- Onkar