From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423146AbWCXFd0 (ORCPT ); Fri, 24 Mar 2006 00:33:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423144AbWCXFd0 (ORCPT ); Fri, 24 Mar 2006 00:33:26 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:27591 "EHLO fgwmail6.fujitsu.co.jp") by vger.kernel.org with ESMTP id S1423148AbWCXFdZ (ORCPT ); Fri, 24 Mar 2006 00:33:25 -0500 Message-ID: <442382F1.2050300@jp.fujitsu.com> Date: Fri, 24 Mar 2006 14:26:09 +0900 From: Kenji Kaneshige User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: ja, en-us, en MIME-Version: 1.0 To: Greg KH CC: Andrew Morton , Linux Kernel Mailing List , linux-pci@atrey.karlin.mff.cuni.cz Subject: [PATCH 2.6.16-mm1 0/4] PCI legacy I/O port free driver (take 6) Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, I've updated the series of patches for PCI legacy I/O port free driver to be applied to 2.6.16-mm1. The previous version of patches conflicts with some changes to e1000 driver. I also confirmed the updated one can be applied to 2.6.16-git7 though I got some warnings. I'm attaching the brief description below about what the problem I'm trying to solve is. Thanks, Kenji Kaneshige Brief Description ~~~~~~~~~~~~~~~~~ I encountered a problem that some PCI devices don't work on my system which have huge number of PCI devices. It is mandatory for all PCI device drivers to enable the device by calling pci_enable_device() which enables all regions probed from the device's BARs. If pci_enable_device() failes to enable any regions probed from BARs, it returns as error. On the large servers, I/O port resource could not be assigned to all PCI devices because it is limited (64KB on Intel Architecture[1]) and it would be fragmented (I/O base register of PCI-to-PCI bridge will usually be aligned to a 4KB boundary[2]). In this case, the devices which have no I/O port resource assigned don't work because pci_enable_device() for those devices failes. This is what happened on my machine. --- [1]: Some machines support 64KB I/O port space per PCI segment. [2]: Some P2P bridges support optional 1KB aligned I/O base. Here, there are many PCI devices that provide both I/O port and MMIO interface, and some of those devices can be handled without using I/O port interface. The reason why such devices provide I/O port interface is for compatibility to legacy OSs. So this kind of devices should work even if enough I/O port resources are not assigned. The "PCI Local Bus Specification Revision 3.0" also mentions about this topic (Please see p.44, "IMPLEMENTATION NOTE"). On the current linux, unfortunately, this kind of devices don't work if I/O port resources are not assigned, because pci_enable_device() for those devices fails.