From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rajesh Shah Subject: Re: [patch 2/2] x86_64: Collect host bridge resources Date: Mon, 23 May 2005 17:57:08 -0700 Message-ID: <20050523175706.A12032@unix-os.sc.intel.com> References: <20050521004239.581618000@csdlinux-1> <20050521004506.842235000@csdlinux-1> <20050523161507.GN16164@wotan.suse.de> Reply-To: Rajesh Shah Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20050523161507.GN16164-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>; from ak-l3A5Bk7waGM@public.gmane.org on Mon, May 23, 2005 at 06:15:07PM +0200 Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Andi Kleen Cc: rajesh.shah-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, len.brown-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, akpm-3NddpPZAyC0@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pci-jyMamyUUXNJG4ohzP4jBZS1Fcj925eT/@public.gmane.org, acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org On Mon, May 23, 2005 at 06:15:07PM +0200, Andi Kleen wrote: > On Fri, May 20, 2005 at 05:42:41PM -0700, rajesh.shah-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org wrote: > > This patch reads and stores host bridge resources reported by > > ACPI BIOS for x86_64 systems. This is needed since ACPI hotplug > > code now uses the PCI core for resource management. This patch > > simply adds the boot parameter (acpi=root_resources) to enable > > the functionality that is implemented in arch/i386. > > > > This means all hot plug users have to pass this strange parameter? > That does not sound very user friendly. Especially since you usually > only need pci hotplug in emergencies, and then you likely didnt pass it. > > Cant you find a way to do this without parameters? Any reason > to not make it default? > I found several systems in which the host bridge was decoding 6+ resource ranges. In the pci_bus structure, I only have room for 4, so I'm forced to drop some ranges that are in fact being passed down. For such cases, if I enable this by default, I see boot time failures for devices that attempted to claim these dropped resources. These devices were otherwise properly configured by BIOS, and work fine with today's (incorrect) assumption that all host bridges decode all unclaimed resources. I didn't want the patch to break existing systems, hence the boot parameter. Another option I'd thought of but never really pursued was to implement this as a late_initcall. I'll look into that some more. In that case, we'd continue to think that all host bridges decode all unclaimed resources at boot time and depend on BIOS to program resources for boot time devices correctly. Later, we'd collect the more accurate host bridge resource picture to make hotplug work correctly. Kind of hackish, but I can't think of another way to avoid the boot parameter. Rajesh ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click