From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261607AbVG2Ay3 (ORCPT ); Thu, 28 Jul 2005 20:54:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262256AbVG2AxC (ORCPT ); Thu, 28 Jul 2005 20:53:02 -0400 Received: from fmr24.intel.com ([143.183.121.16]:55009 "EHLO scsfmr004.sc.intel.com") by vger.kernel.org with ESMTP id S262258AbVG2Awg (ORCPT ); Thu, 28 Jul 2005 20:52:36 -0400 Date: Thu, 28 Jul 2005 17:52:17 -0700 From: Rajesh Shah To: Rajat Jain Cc: Kristen Accardi , greg@kroah.com, linux-kernel@vger.kernel.org, linux-newbie@vger.kernel.org, acpi-devel@lists.sourceforge.net, linux-hotplug-devel@lists.sourceforge.net, dkumar@noida.hcltech.com Subject: Re: Re: Problem while inserting pciehp (PCI Express Hot-plug) driver Message-ID: <20050728175217.A1821@unix-os.sc.intel.com> Reply-To: Rajesh Shah References: <20050725021747.67869.qmail@web34405.mail.mud.yahoo.com> <512afbf905072711295f87ad24@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from rajat.noida.india@gmail.com on Thu, Jul 28, 2005 at 07:45:49PM +0900 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 28, 2005 at 07:45:49PM +0900, Rajat Jain wrote: > > Okay. I'm sorry but I'm not very clear with this. I'm just putting > down here my understanding. So basically we have two mutually > EXCLUSIVE hotplug drivers I can use for PCI Express: > A hotplug slot can be controlled only by a single hotplug technology - pcie shpc or acpiphp. However, different parts of the I/O hierarchy can be controlled by different technologies. For example, a host bridge I/O complex can be hotplugged using acpiphp, but end devices under this IO complex may be hotpplugged using pcie or shpc hotplug. > 1) "pciehp.ko" : We use this PCIE HP driver when our BIOS supports > Native Hot-plug for PCI Express (which means that hot-plug will be > handled by OS single handedly). > > 2) "acpiphp.ko" : We use this "generic" ACPI HP driver when BIOS > allows only ITSELF to handle hot-plug events. > No, acpi hotplug is not handled by BIOS only. Both acpi and pcie hotplug need firmware support as well as hardware support. Hardware in many (but not all) systems support both types of hotplug and its up to the BIOS to decide which type to support. If the platform supports pcie hotplug, you see an _OSC & _SUN methods in the ACPI namespace and the pciehp driver controls hotplug slots. If the system supports acpi hotplug, you see _ADR and _EJ0 methods in the ACPI namespace and the acpiphp driver controls the corresponding hotplug slots. Rajesh